JTAM (Jurnal Teori dan Aplikasi Matematika)

Journal Information
ISSN / EISSN : 2597-7512 / 2614-1175
Current Publisher: Universitas Muhammadiyah Mataram (10.31764)
Total articles ≅ 103
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Latest articles in this journal

Abdul Nu'Man Asok, A Hasanah
JTAM (Jurnal Teori dan Aplikasi Matematika), Volume 5, pp 254-261; doi:10.31764/jtam.v5i1.3929

Abstract:
The aim of this research is to find the difficulties of students in solving word problems in the three-variable linear equation systems subject. Before they took a mathematical problem-solving exam, the learners were given reinforcement of prerequisite knowledge of the intended subject. The problem-solving test indicators used in this study were taken from Polya's problem-solving steps consisting of (1) recognizing the question, (2) making a plan for problem-solving (developing a plan), (3) implementing the plan for problem-solving, and (4) looking back. The research method used in this study was a qualitative descriptive. The subject in this study was 15 students who were 10 th graders of senior high school. The data were obtained from a student performance who took mathematical problems solving test. The result obtained from this study can be seen from the number of students whose achievement indicators formulate a plan of 49.6%, achievement in completing plans 14.1%, and achievement in checking solutions 2.2%. However, the indicators of understanding the problem area in the good category, namely 80%. The result of this study showed that the students were only able to solve the word problems for understanding the problem (good category) and devising the plan steps (mediocre category), whereas they got difficulties in solving the word problems in carrying out the plan and looking back (low category).
Willy Abdul Ghany, Wahyudin Wahyudin
JTAM (Jurnal Teori dan Aplikasi Matematika), Volume 5, pp 225-235; doi:10.31764/jtam.v5i1.3919

Abstract:
Mathematics is seen by some students as a subject which is not easy to learn. Thus, they need someone who can make mathematics easy, in this point, a teacher. Teachers as instructor are needed to be more innovative in developing instruction that can encourage students to get an ideal learning experience. Not just regarding approaches, teaching materials, and strategies, yet additionally needs to focus on the learning environment which promotes the learning process. One of the framework that offers learning which takes into a supportive learning environment is the Productive Pedagogies Framework. The purpose of this study is to look at the implementation of learning that utilized the Supportive Classroom Environment dimension of the Productive Pedagogies Framework. This study used qualitative method. There were 33 grade VII students (boys and girls) on average age of 13 years old from one of the Junior High Schools in Bandung participated in this study. The research findings revealed that (1) implementing Supportive Classroom Environment can further encourage students in upper group to achieve more optimal learning outcomes; (2) This learning can be said to encourage middle group students to get optimal learning outcomes; (3) This learning has not been able to encourage students in lower group. We concluded that implementing Supportive Classroom Environment can further encourage students in upper and middle groups.
Agus Haerani, Khusnul Novianingsih, Turmudi Turmudi
JTAM (Jurnal Teori dan Aplikasi Matematika), Volume 5, pp 246-253; doi:10.31764/jtam.v5i1.3928

Abstract:
Many students in the world have difficulty in solving word problems, including students in Indonesia. TIMSS has shown that only eight percent of Indonesian participants are able to solve word problems, this result is hugely lower than the international average of 18 percent. One of the factors that cause students' errors in solving word problems is mathematical resilience. Thus, this study aims to analyze students' misconceptions in solving word problems viewed by their mathematical strength. This study was conducted for sixth-grade students in one of the elementary schools in Bandung. This study was qualitative descriptive research. In this study, there were four steps: selecting the word problems, answering the issues, filling out a mathematical resilience questionnaire, and interviewing. Students were encouraged to respond to a three-word question within 30 minutes, filling out a mathematical resilience questionnaire followed by the interview. This study showed that the students' errors in solving word problems were including comprehension, transformation, and process skill errors. Based on mathematical resilience, students with a low level of resilience predominantly carried out comprehension errors. In contrast, students with a moderate level of resilience more dominant made transformation errors. Meanwhile, students with high resilience completed more questions correctly, although several students seemed to have made process skills errors. This study's limitation is the data obtained online so that the respondents completed the instrument exceeds the given time. Further researches are suggested to conduct directly in the classroom to maximize the accuracy of the study.
Sugiyarto Sugiyarto, Joko Eliyanto, Nursyiva Irsalinda, Zhurwahayati Putri, Meita Fitrianawat
JTAM (Jurnal Teori dan Aplikasi Matematika), Volume 5, pp 110-120; doi:10.31764/jtam.v5i1.3766

Abstract:
Sentiment analysis is an analysis with an objective to identify like, dislike, comments, opinion, or feedback on certain content which will be categorized into positive, negative, or neutral. In general selection, sentiment analysis widely known to be used to predict the winner on election process. This method tries to dig the people sentiment on their governor candidates during election, whether it’s positive, negative, or neutral opinion. The output of the positive sentiment is related to people acceptance towards one of the election nominee. That statement usually applied as a base reference for determining the result of the election process. In sentiment analysis, the importance of its fuzzy logics must be considered. Each of the people statement is assumed to have the level of positive, negative, or neutral percentage. The concept of fuzzy logic is developed and applied on one of this text mining method. This research is focusing on comparison analysis and fuzzy logic application in sentiment analysis method. Two method which discussed in this research are Fuzzy Naïve Bayes and Sentiment Fuzzy with convolutional neural network. This research is applied on PILKADA of Solo and Medan district case study. The data of the people opinion are acquired from twitter and collected on September 2020 to December 2020. The two methods which mentioned before are implemented on the acquired data and the output of these method application then compared. The conclusion of this research suggest that different approach will resulting in different output.
Irwan Kasse, Andi Mariani, Serly Utari, Didiharyono D.
JTAM (Jurnal Teori dan Aplikasi Matematika), Volume 5, pp 1-13; doi:10.31764/jtam.v5i1.3220

Abstract:
Investment can be defined as an activity to postpone consumption at the present time with the aim to obtain maximum profits in the future. However, the greater the benefits, the greater the risk. For that we need a way to predict how much the risk will be borne. Modelling data that experiences heteroscedasticity and asymmetricity can use the Asymmetric Power Autoregressive Conditional Heteroscedasticity (APARCH) model. This research discusses the time series data risk analysis using the Value at Risk-Asymmetric Power Autoregressive Conditional Heteroscedasticity (VaR-APARCH) model using the daily closing price data of Bitcoin USD period January 1 2019 to 31 December 2019. The best APARCH model was chosen based on the value of Akaike's Information Criterion (AIC). From the analysis results obtained the best model, namely ARIMA (6,1,1) and APARCH (1,1) with the risk of loss in the initial investment of IDR 100,000,000 in the next day IDR 26,617,000. The results of this study can be used as additional information and apply knowledge about the risk of investing in Bitcoin with the VaR-APARCH model.
Ulfa Lu'Luilmaknun, Karin Selma Al Kautsar, Ratih Ayu Apsari, Tabita Wahyu Triutami, Nourma Pramestie Wulandari
JTAM (Jurnal Teori dan Aplikasi Matematika), Volume 5, pp 60-69; doi:10.31764/jtam.v5i1.3309

Abstract:
Blended learning is a learning that combines face-to-face and online learning. Several studies have shown that blended learning has a positive effect on collaborative skills. The aim of this study is to determine the collaborative skills of pre-service mathematics teachers after using blended learning. The focus of this study is 4 indicators of collaborative work skills, namely quality of work, problem solving skills, working with others, and focus on the task. This type of study is a case study. The participants were 23 pre-service mathematics teachers in second year. Data collection was carried out using a collaborative questionnaire. Data were analysed using quantitative descriptive methods. The results showed that the criterion for quality work of students was 47.83% average. The criterion for problem solving skills was 47.83% very high. The criterion of working with others was 86.96% very high. The criterion for focus on the task was 82.61% very high. Therefore, blended learning possesses positive effects towards pre-service mathematics teachers.
Suryasatriya Trihandaru, Hanna Arini Parhusip, Bambang Susanto, Yohanes Sardjono
JTAM (Jurnal Teori dan Aplikasi Matematika), Volume 5, pp 88-99; doi:10.31764/jtam.v5i1.3468

Abstract:
The research purpose shown in this article is describing the time dependent reproduction number of coronavirus called by COVID-19 in the new normal period for 3 types areas, i.e. small, medium and global areas by considering the number of people in these areas. It is known that in early June 2020, Indonesia has claimed to open activities during the pandemic with the new normal system. Though the number of COVID-19 cases is still increasing in almost infected areas, normal activities are coming back with healty care protocols where public areas are opened as usual with certain restrictions. In order to have observations of spreading impact of COVID-19, the basic reproduction number (Ro) i.e. the reproduction number (Ro) is the ratio between 2 parameters of SIR model where SIR stands for Susceptible individuals, Infected individuals, and Recovered individuals respectively. The reproduction numbers are computed as discrete values depending on time. The used research method is finite difference scheme for computing rate of change parameters in SIR models based on the COVID-19 cases in Indonesia (global area), Jakarta (medium area) and Salatiga (small area) by considering the number of people in these areas respectively. The simple forward finite difference is employed to the SIR model to have time dependent of parameters. The second approach is using the governing linear system to obtain the values of parameter daily. These parameters are computed for each day such that the values of Ro are obtained as function of time. The research result shows that 3 types areas give the same profiles of parameters that the rate of changes of reproduction numbers are decreasing with respect to time. This concludes that the reproduction numbers are most likely decreasing.
Arun Kumar Rao, Himanshu Pandey
JTAM (Jurnal Teori dan Aplikasi Matematika), Volume 5, pp 28-35; doi:10.31764/jtam.v5i1.3268

Abstract:
In this paper, length biased Weibull distribution is considered for Bayesian analysis. The expressions for Bayes estimators of the parameter have been derived under squared error, precautionary, entropy, K-loss, and Al-Bayyati’s loss functions by using quasi and gamma priors.
Tabita Wahyu Triutami, Uun Hariyanti, Dwi Novitasari, Ratna Yulis Tyaningsih, Junaidi Junaidi
JTAM (Jurnal Teori dan Aplikasi Matematika), Volume 5, pp 36-49; doi:10.31764/jtam.v5i1.3280

Abstract:
Creativity is very necessary for learning mathematics, especially when solving geometry problems. This research aims to describe 4th year mathematics education students’ creativity in solving geometry problems. Creativity in this research is focused on fluency, flexibility, and originality of student anwer when solving geometry problems. This research is an explorative descriptive research through a qualitative approach. The participants were 7 fourth year mathematics education students of state University in Mataram, who have a high level of visual-spatial intelligence. The data was collected by written test and interview. The test consisted of two open-ended geometry problems about transforming 3-dimensional images into 2-dimensional images and making 2-dimensional images with a predetermined circumference. The problems are modification of the 2006 PISA test. The result showed that subjects with high visual-spatial intelligence levels met all indicators of creativity. In solving problems that meet the aspects of fluency, flexibility and originality, they combine mental rotation and mental visualization abilities and include using their visual experience by modifying the information obtained and the initial problem solving ideas obtained. This also enables them to produce original problem solutions. The results of this research can be used as an illustration and a guideline to assess students’ creativity with high visual-spatial intelligence level.
Farizi Rachman, Dhika Aditya Purnomo, Ridhani Anita Fajardini, Rena Riza Umami
JTAM (Jurnal Teori dan Aplikasi Matematika), Volume 5, pp 50-59; doi:10.31764/jtam.v5i1.3291

Abstract:
This research aims to obtain optimal value for the surface roughness of the material AISI P20 on the Electrical Discharge Machining (EDM) Sinking process. In the present research, the Taguchi method is used to investigate the significant influence of process variables on the machining performance and determine the combination of process variables on the EDM process. Orthogonal array L18 (21 × 33) based on the Taguchi method is chosen for the design of experiment. The experiment is replicated twice to finding out the influence of four process variables such as type of electrode, voltage gap, on-time, and off-time on the response performance. Machining performance is evaluated by surface roughness as a response variable that had quality characteristics, smaller is better. These experimental data were analyzed using the Signal-to-noise ratio and Analysis of Variance. The analysis results show that the surface roughness is influenced by the type of electrode and on time. Combination of process variables to obtain optimal surface roughness are using graphite electrodes, and setting values of gap voltage 40 volt, on-time 250 μs, and off-time 20 μs. This combination of process variables can be applied to the manufacturing process using EDM sinking in order to produce a good quality product that determined based on the surface roughness value.
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