Question

Q.7 If a + b = 1 and a² + b2 = 85, then the value of
(a3 + b3), is
(A) 127
(B) 173
(C) 154
(D) 321​

Answer 1

Answer:

(a2+b2)=(a+b)2-2ab

or (a+b)2-2ab=85

or 1-2ab =85

or ab=-42

then (a3+b3)=(a+b) (a2 -ab + b2)

=1(85-(-42))

=(85+42)

127