Question

(a^2+b^2)(-a^2+b^2)​

Answer 1

( a² + b²) ( - a² + b²)

=> a²( - a²+ b²) + b²( - a²+ b²)

=> - a⁴ + a²b² - b²a² + b⁴

=> - a⁴ + b⁴

hence your answer => - a⁴ + b⁴

Answer 2

Answer:

if a+b= 2 then you might want to elevate the whole equation to the square which gives:

(a+b)² = 2² = 4

you also know that (a+b)² = a² + b² + 2ab = 4

Replace a²+b² in the latest equation since you know that a²+b² = 6

then you will get: 6 + 2ab = 4 -> 2ab = 4-6 = -2 Q.E.D