Question

Solve the system by the

substitution method.
Sol
of
x + 7y = -1
- 4x – 2y = -22

Answer 1

First make x stand alone: x= -7y-1

Substitute this to where you find the letter x in the second equation

-4(-7y-1)-2y=-22

Multiply the -4 by the numbers in the parentheses and son't forget your signs

28y+4-2y=-22

26y=-22-4

26y=26

Divide both sides by 26

y= -1

Substitute -1 in the 3 equation to find x

X= -7y-1

=-7(-1)-1

=7-1

X= 6

Explanation:

Answer 2

(6, - 1 )

Explanation:

Given the 2 equations

x + 7y = - 1 → (1)

- 4x - 2y = - 22 → (2)

Rearrange (1) expressing x in terms of y by subtracting 7y from both sides

x = - 1 - 7y → (3)

Substitute x = - 1 - 7y into (2)

- 4(- 1 - 7y) - 2y = - 22 ← distribute and simplify left side

4 + 28y - 2y = - 22

4 + 26y = - 22 ( subtract 4 from both sides )

26y = - 26 ( divide both sides by 26 )

y = - 1

Substitute y = - 1 into (3) for corresponding value of x

x = - 1 - 7(- 1) = - 1 + 7 = 6

Solution is (6, - 1 )