Question

x-y=7 and xy=9 find the value of x2+y2

Answer 1

We have,
x-y =7, x-y =9

We know
(x-y)^2 = x^2 + y^2 -2xy
(7)^2 = x^2 + y^2 - 2(9)
49 = x^2 + y^2 - 18
49+18 = x^2 + y^2
67 = x^2 + y ^2
I.e. x^2 + y^2 = 67. Ans

Answer 2

hey mate!!

as x-y=7so
x=7+y

and xy=9
so x=9/y


you can fill any valuein x2+y2

(9/y)2+(9/x)2=0
81/y2+81/x2=0
81x2+81y2=0
81(x2+y2)=0

x2+y2=0