4x2+26x=40

Solution for 4x2+26x=40 equation:

4x^2+26x=40

We move all terms to the left:

4x^2+26x-(40)=0

a = 4; b = 26; c = -40;
Δ = b2-4ac
Δ = 262-4·4·(-40)
Δ = 1316
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:

$\sqrt{\Delta}=\sqrt{1316}=\sqrt{4*329}=\sqrt{4}*\sqrt{329}=2\sqrt{329}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(26)-2\sqrt{329}}{2*4}=\frac{-26-2\sqrt{329}}{8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(26)+2\sqrt{329}}{2*4}=\frac{-26+2\sqrt{329}}{8}
$