How do you solve this system of equations: a+ b = 4 and a - b = 10a+b=4andab=10?

1 Answer
Oct 24, 2017

a=7a=7 and b=-3b=3

Explanation:

If a+b=4a+b=4 and we subtract bb from both sides, we get a=4-ba=4b

a-b=10ab=10
Since we know that a=4-ba=4b, we can substitute aa with that.
4-b-b=10->4bb=10
4-2b=1042b=10

Subtract 44 from both sides:
-2b=10-4->2b=104
-2b=62b=6

Divide both sides by -22

(-2b)/(-2)=6/(-2)->2b2=62
b=-3b=3

Since we know a=4-ba=4b and b=-3b=3, a=4-(-3)a=4(3) which is equal to a=7a=7.