Question

For the following system, if you isolated x in the first equation to use the Substitution Method, what expression would you substitute into the second equation?

x - 2y = -4
3x + y = 12

A) -2y - 4
B) 2y - 4
C) 2y + 4
D) -2y + 4

Answer 1

For the system of equations x - 2y = -4 and 3x + y = 12, if x is isolated in the first equation, the expression 2y - 4 should be substituted into the second equation.

Step-by-step explanation:

To solve the given system of equations by the Substitution Method, we must first isolate x in the first equation:

x - 2y = -4

Adding 2y to both sides we get:

x = 2y - 4

This expression for x is then substituted into the second equation.

3x + y = 12

Substituting for x we get:

3(2y - 4) + y = 12

Based on this, the correct expression to substitute into the second equation would be 2y - 4, which corresponds to option B).