How do you solve the system 7x + 2y = 2 and 6x - 2y = 8?

1 Answer
May 16, 2015

I notice that all the terms in the second equation are divisible by 2 and it will be easy to isolate y, so let's do that first.

6x-2y=8

Divide both sides by 2 to get

3x-y=4

Add y to both sides to get

3x=4+y

Subtract 8 from both sides to get

y = 3x-4

Now substitute this expression for y into the first equation...

2 = 7x+2y

= 7x + 2(3x-4)

= 7x + 6x - 8

=13x - 8

Add 8 to both sides to get

13x=10

Divide both sides by 13 to get

x = 10/13

y = 3x-4 = (3xx10)/13-4

= 30/13-(4xx13)/13

= (30-52)/13

= -22/13