Question

sendo a+b= 4 e a -B =2 calcule o valor de a²-b²

Answer 1

$\left \{ {{a+b=4} \atop {a-b=2}} \right.$  ---> corta o b.

2a=6

a=$\frac{6}{2}$

a=3

a+b=4 ---> 3+b=4    ---> b=4-3  --->b=1

a²+b²=3² + 1²= 9-1 =8