Question

Find the value of x²+y² if
x+y=9 xy=14​

Answer 1

Explanation:

It's a system of equations.

From the first one we isolate x:

x = 9-y

And we substitute in the second one:

(9-y)y = 14

-y^2 + 9y - 14 = 0

y^2 - 9y + 14 = 0

D = 25

y1/2 = (9 +- 5)/2 = 2 or 7

y = 2 => x = 7

y = 7 => x = 2

x^2 + y^2 = 7^2 + 2^2 = 53