Question

find the value of x3+y3+12xy-64 when x+y=1

Answer 1

Given,.
x+y=1....but if we make cube of both sides we will not get 64 in any Terms 64 is the cube of 4 and again ......
we need 12xy =3xy *4....
observing that it seems that question should be like This..

find the value of x3+y3+12xy-64 when x+y=4...
now see picture!!...
hope you understand!!