Question

已知x-y=5,(x+y)^2=49,求x²y²的值

Answer 1

x-y=5

(x-y)^2=25

x^2+y^2-2xy=25

(x+y)^2=49

x^2+y^2+2xy=49

4xy=24

xy=6

x^2y^2=(xy)^2=36