Question

if x+y=8then find the value of xy?

Answer 1

Answer:

x+y =8

x= 8-y

y= 8-x

xy = (8-y)(8-x)

=64+(-y-x)8 +(-y × -x)

=64 -8x-8y +xy

-xy = -8x -8y +64

xy = 8x +8y -64

xy = 8( x+y -8)