Kay solves the following system of equations using the substitution method. y=−4x+2
3x−y=9

What is the single-variable equation she solves after substituting?

3x−(−4x+2)=9

3x−4x+2=9

3x+9=−4x+2

3x+9=−(4x+2)
PLZ HELP ME SOON

The single-variable equation she solves after substituting is 3x−(−4x+2)=9

They are expressions separated by an equal sign.

Given the system of equations:

To get the required single-variable equation, we will substitute equation 1 into 2 to have:

3x - y = 9

3x - (-4x + 2) = 9

Expand

3x + 4x - 2 = 9

7x = 9 + 2

7x - 11 = 0

Hence the single-variable equation she solves after substituting is 3x−(−4x+2)=9

Learn more on single-variable equation here: link

the polynomial is a perfect square trinomial of the form a^2-2ab+b^2:

option a. true

step-by-step explanation:

9x^2-12x+4

comparing with the form a^2-2ab+b^2

1.) a^2=9x^2

solving for a: square root both sides of the equation:

sqrt(a^2)=sqrt(9x^2)

a=sqrt(9) sqrt(x^2)

a=3x

2.) b^2=4

solving for b: square root both sides of the equation:

sqrt(b^2)=sqrt(4)

b=2

to be a perfet square trinomial 2ab must be equal to 12x. let's check:

2ab = 2 (3x) (2)

2ab = 12x

correct