Question

If x+y=10 and xy=21 find 2(x square + y square)

Answer 1

Hey!!!!

_________

We have

=> x + y = 10
and
=> xy = 21

Then To Find = 2(x² + y²)

Proof : Using Given,

=> x + y = 10

Square both sides

=> (x + y)² = 100

=> x² + y² + 2xy = 100

=> x² + y² + 2(21) = 100 (given)

=> x² + y² = 58

Multiply by 2 on both sides

=> 2(x² + y²) = 116

Hence Found

_________

Hope this helps ✌️

Good Morning:)

Answer 2

(x+y)² = x²+y²+2xy

10² = x²+y²+ 2*21

100 = x²+y²+42

x²+y² = 100-42 = 58

So, 2(x²+y²) = 2*58
                    = 116

Hope this helpz :)