Question

Which of the following equations shows how substitution can be used to solve the following system of equations? {y=2x−7{3x+4y=16 A) 3x + 4y = 2x - 7B) 3(2x - 7) + 4y = 16C) 3x + 4(2x - 7) = 16D) y = -7

Answer 1

The substitution method works by solve one equation for some variable and then plug-in this equation into the other one.

Then in this case, we already have the first equation in the form of y=--- (solved for y). Then the next step is replace this y=2x-7 into the second equation as follows:

`\begin{gathered} 3x+4y=16 \\ 3x+4(2x-7)=16 \end{gathered}`

Which is the very same as the option C. Hence the answer is C) 3x+4(2x-7)=16