Question

For the following system, if you isolated x in the second equation to use the Substitution Method, what expression would you substitute into the first equation? 2x + y = 8
−x − 3y = −12

Answer 1

-x - 3y = -12
-x = 3y - 12..multiply by -1 to make x positive
x = -3y + 12
so u would sub in -3y + 12 for x in the first equation

Answer 2

Answer:

$x=12-3y$

Step-by-step explanation:

Question wants to know WHAT EXPRESSION would you substitute into Equation 1 IF you solve for x in Equation 2.

Let's do some algebra and solve for x in Equation 2:

$-x-3y=-12\\-x=-12+3y\\x=\frac{-12+3y}{-1}\\x=12-3y$

This is the expression we would substitute into  $x$  of Equation 1 in order to use substitution method and solve.