Solve the following system, by graphing or substitution?

Question

3x-y=9
2x+y=6

5x-2y=20
-2x+y=-10


x-y=6
x+y=7

Answer 1

I will solve the last system for you, to show you how it's done. I always prefer substitution.

x - y = 6
x + y = 7

First, rewrite the first equation to give an expression for x.

x = y + 6

Now, use this expression in place of x in the second equation.

(y + 6) + y = 7

Now solve algebraically, which is simple.

2y + 6 = 7
2y = 1
y = 0.5

Finally, use this value for y in the expression for x.

x = y + 6 = 0.5 + 6 = 6.5

The solution is x = 6.5 and y = 0.5, or (6.5, 0.5).

Answer 2

I used substitution
3x-y=9
2x+y=6
the y's cancel & your left with:
3x=9
2x=6
5x=15
x=3
then put 3 back in for x :
2(3)+y=6
6+y=6
y=0
You can check your answer by putting in 3 & 0 for x & y

Answer 3

1st- x=3
y=0
2nd-x=0
y=-10
3rd-x=13/2
y=1/2