For the following system use the second equation to make a substitution for y in the first equation 2x+y=5 y+3=2x

1. Substitution: x = y + 10

3x + 2y - 5 = 0

3 (y + 10) + 2y = 5

3y + 2y = 5 - 30

5y = - 25

y = - 5 (answer)

2. Replace x with 2y - 8 in the first equation.

2y + 5y = 18

7y = 18

Simplest form: 7y - 18 = 0, or (c) (answer)

3.

q = 1 - 2p

3p + q + 1 = 0

q = - 1 - 3p

1 - 2p = - 1 - 3p

p = - 2

Substitute:

-1 - 3 (-2) = - 1 + 6 = q = 5

Solution set:

{ (-2,5) }, or (a) (answer)

4.

y = 5x - 4

3x + 5x - 4 = 1, or (a) (answer)

5.

y = x + 1

2x + x + 1 = 7

3x = 6

x = 2

y = 1 + 2 = 3

Now replace x with 2 and y with 3 in all of the answers and see which one doesn't work.

a: 7 - 4 - 2 = 1 this works

b: 4 + 2 + 1 = 7 this works

c: 2 (4) + 3 = 7 8 + 3 = 11, not 7

(c) would not be the result of the system. (answer)

6.

x = y - 3

3 (y - 3) + 2y = 7, or (b) (answer)