Question

se X+Y=11 e X-Y=5, então o valor de X^2-Y^2 é?

Answer 1

{x+y=11
{x-y=5
2x=16
x=16/2
x=8
x-y=5
8-y=5
-y=5-8
-y=-3.(-1)
y=3
x^2-y^2
8^2-3^2
64-9
55