Question

Use the substitution method to solve the following system of equations.

4x – y = 3
7x – 9y = –2

Answer 1

4x – y = 3 --> transform into y=4x-3
7x – 9y = –2

y=4x-3
7x – 9y = –2 -- sub in

7x-9(4x-3)=-2

7x-36x+27=-2

-29x=-29

x=1

sub back in

y=4(1)-3

y=1

solution x=1 y=1

Answer 2

y = 4x - 3
y = (2+ 7x)/9

Set y = y

9(4x-3) = 2 + 7x

36x - 27 = 2 + 7x

29 = 29x

x = 1
y = 1