Givens
x + y = 3
x =6 - 4y
Solution
Use the top equation to substitute for x in the second equation.
x = 3 - y
Put this result into the second given equation and solve for y
3 - y = 6 - 4y Add 4y to both sides.
3 - y + 4y = 6 Combine on the left
3 + 3y = 6 Subtract 3 from both sides
3 - 3 + 3y = 6 - 3 Combine
3y = 3 Divide by 3
3y/3 = 3/3 Combine
y = 1
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x + y = 3 but y = 1
x + 1 = 3 Subtract 1 from both sides.
x + 1 - 1 =3 - 1
x = 2
Answer
x = 2
y = 1
G(-4) = 4^2 + 3(-4) - 2
16 - 12 - 2
4 - 2
answer: 2
Plug in 6.5 for x.
-8.5x-3.5x=-78
-8.5(6.5)-3.5(6.5)=-78
-55.25-22.75=-78
-78=-78
