25=4x+3x*x

Solution for 25=4x+3x*x equation:

25=4x+3x*x

We move all terms to the left:

25-(4x+3x*x)=0

We add all the numbers together, and all the variables

-(+4x+3x*x)+25=0

We get rid of parentheses

-4x-3x*x+25=0

Wy multiply elements

-3x^2-4x+25=0

a = -3; b = -4; c = +25;
Δ = b2-4ac
Δ = -42-4·(-3)·25
Δ = 316
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{316}=\sqrt{4*79}=\sqrt{4}*\sqrt{79}=2\sqrt{79}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-4)-2\sqrt{79}}{2*-3}=\frac{4-2\sqrt{79}}{-6}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-4)+2\sqrt{79}}{2*-3}=\frac{4+2\sqrt{79}}{-6}
$