x2+7x=40

Solution for x2+7x=40 equation:

x2+7x=40

We move all terms to the left:

x2+7x-(40)=0

We add all the numbers together, and all the variables

x^2+7x-40=0

a = 1; b = 7; c = -40;
Δ = b2-4ac
Δ = 72-4·1·(-40)
Δ = 209
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(7)-\sqrt{209}}{2*1}=\frac{-7-\sqrt{209}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(7)+\sqrt{209}}{2*1}=\frac{-7+\sqrt{209}}{2}
$