Question

If x+y=15 and xy=54. Find the value of x^2-y^2..

Answer 1

x=6 and y=9 or x=9 and y=6 ....answer is +45 or - 45

Answer 2

=(x-y) (x+y)
=x^2-2xy+y^2
=(x+y)^2-2xy
=(15)^2-2(54)
=225-108
=117
may be this is right procedure but I m not sure