2x(5x+2)=26

Solution for 2x(5x+2)=26 equation:

2x(5x+2)=26

We move all terms to the left:

2x(5x+2)-(26)=0

We multiply parentheses

10x^2+4x-26=0

a = 10; b = 4; c = -26;
Δ = b2-4ac
Δ = 42-4·10·(-26)
Δ = 1056
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:

$\sqrt{\Delta}=\sqrt{1056}=\sqrt{16*66}=\sqrt{16}*\sqrt{66}=4\sqrt{66}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(4)-4\sqrt{66}}{2*10}=\frac{-4-4\sqrt{66}}{20}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(4)+4\sqrt{66}}{2*10}=\frac{-4+4\sqrt{66}}{20}
$