36=2x(2x+5)

Solution for 36=2x(2x+5) equation:

36=2x(2x+5)

We move all terms to the left:

36-(2x(2x+5))=0


We calculate terms in parentheses: -(2x(2x+5)), so:

2x(2x+5)

We multiply parentheses

4x^2+10x

Back to the equation:

-(4x^2+10x)


We get rid of parentheses

-4x^2-10x+36=0

a = -4; b = -10; c = +36;
Δ = b2-4ac
Δ = -102-4·(-4)·36
Δ = 676
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{676}=26$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-10)-26}{2*-4}=\frac{-16}{-8}
=+2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-10)+26}{2*-4}=\frac{36}{-8}
=-4+1/2
$