The expansion of (x+y)3 is
x3 + y3 + 3x2y - 3xy2
x3 + y3 - 3x2y + 3xy2
x3- y3 - 3x2y + 3xy2
x3 + y3 + 3x2y + 3xy2
(x+y)3=(x+y)(x+y)2=(x+y)(x2+2xy+y2)
(x+y)3=x(x2+2xy+y2)+y(x2+2xy+y2)=x3+2x2y+xy2+x2y+2xy2+y3 =x3+y3+3x2y+3xy2
The expansion of (x+y)3 is x3+y3+3x2y−3xy2
Question 59 (a)
What should be added to x3+3x2y+3xy2+y3 to get x3+y3?