Find the values of a^2 + b^2 and a^4 + b^4 when a + b = 5 and Ab = 4.

Answer 1

(a+b)^2 = a^2 + 2ab + b^2
So,
5^2 = 2*4 + a^2+b^2
a^2+b^2 = 17

Now do the next, knowing that
(a^2+b^2)^2 = a^4 + 2a^2b^2 + b^4