X+y=7X2+y2=25

Solution for X+y=7X2+y2=25 equation:

X+X=7X^2+X2=25

We move all terms to the left:

X+X-(7X^2+X2)=0

We add all the numbers together, and all the variables

2X-(7X^2+X2)=0

We get rid of parentheses

-7X^2+2X-X2=0

We add all the numbers together, and all the variables

-8X^2+2X=0

a = -8; b = 2; c = 0;
Δ = b2-4ac
Δ = 22-4·(-8)·0
Δ = 4
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{4}=2$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(2)-2}{2*-8}=\frac{-4}{-16}
=1/4
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(2)+2}{2*-8}=\frac{0}{-16}
=0
$