Question

If x-y=7 and x^3-y^3=133, find x^2-y^2

Answer 1

Step-by-step explanation:

x^3-y^3=133

or,(x-y)(x^2+xy+y^2)=133

or,x^2+xy+y^2=19

or,x^2+y^2=19-xy

or,(x-y)^2+2xy=19-xy

or 49=19-3xy

or,-3xy=30

or,xy=-10

x^2-y^2

=7x+7y

=7(x+y)

=7(-10/y-10/x)