Question

Find the value of x2+y2 when: x+y=7 and xy=10

Answer 1

Hey there !

Thanks for the question !

Here's the answer !

( x + y )² = x² + y² + 2xy

=> x² + y² = ( x + y )² - 2xy

We are given that,

x + y = 7 ; xy = 10

=> x² + y² = ( 7 )² - 2 ( 10 )

=> x² + y² = 49 - 20

=> x² + y² = 29

Hence 29 is the required solution.

Hope my answer helped !

Answer 2

X^2+y^2 can be written as

=>(X+y)^2= X^2+y^2 +2xy

=>X^2+y^2 = (X+y)^2- 2xy

=>X^2+y^2 = (7)^2+2(10)

=>X^2+y^2 = 49-20

=>X^2+y^2 = 29

Hope it helps u definitely