Question

If a+b=11 and a2+b2=61 then find the value of a3+b3

Answer 1

the value of a3+b3=72

Answer 2

(a+b)3 = a3+b3+3a2b+3ab2
a3+b3= (a+b)3-3a2b-3ab2
= (11)3-3(61-b2)b-3a(61-a2)
=121-183b-3b3-183a-3a3
=121-183b-183a-3a3-3b3
=121-183(a+b)-3(a3+b3)
=121-183(11)-3(a3+b3)
=121-2013-3(a3+b3)
=-1892-3(a3+b3)
I think this is the answer...