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Question
Solve by the substitution method
9x+5y=3
x=45-8y
Hello Melissa
These equations are called simultaneous equations, because the solution you find satisfies both equations.
So, substitution method is all about finding the formula of one variable in terms of the other and substituting this same formula in the second equation.
Without further ado, let’s find X in terms of Y. But as you can see X is already written in terms of Y in the second equation. Good choice.
I just have to substitute this formula in place of X in the first equation, so that I deal with only one variable, Y.
9(45 – 8Y) + 5Y = 3
405 – 72Y + 5Y = 3
405 – 67Y = 3
405 – 3 = 67Y
402 = 67Y
6 = Y
What remains is the value of X, which I can find easily.
Just substitute 6 in place of every Y to find the value of X.
9X + 5*6 = 3
9X + 30 = 3
9X = -27
X = -3
So the solution is {-3, 6}
Melissa, I started to give some tutorials (questions with answers and short notes) to some students. I preferred the postal system because most of the work is done on paper. If you want to be one of them just send me a notification email.
ALWAYS READY TO HELP YOU
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Answers by Expert:
Michael Tadesse
Expertise
I can answer questions regarding Relations, linear functions and equations, Squares and square roots, Translation and Similarity, Special Properties of Right Angled Triangles, Measurement of Area and Volume, algebra. I can also answer questions related to Pre calculus, Limits and Continuity, Derivatives Applications of Derivatives, High school math in general. I can’t answer questions of the following type. Power Series, Multiple Integrals, Fourier series, Vector valued Functions.
Experience
I love mathematics as it is the mother of all sciences. I had an outstanding math results while I was in school. The tradition continues while I am in university. I have been helping elementary school Students for the past five years with mathematics problems. In fact, I have a brother who is four years younger than me I usually help him to understand what the crux of the question is before trying to solve it. He loves math very much, he is indeed one of the top scorers form his class in Mathematics. I didn’t stop helping my younger relatives after I joined the Engineering campus and I am more than ready to help anyone with my skill.
Education/Credentials
have a high school diploma with a 3.97 GPA; I also have many merit certificates granted for my outstanding results in high school math. I won a merit certificate for my participation in the Black Month Essay Contest. I took two different National Examinations in 2006 and 2007. In the former Exam I got 9As which includes Mathematics. I also have a score of 90 out of hundred in the later Examination which is the toughest known in Ethiopia. So you don’t have to worry about my ability to help my clients.
Past/Present Clients
I have never had an online client but I was helping students coming to me for assistance in Mathematics.
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