d*d+3d-88=0

Solution for d*d+3d-88=0 equation:

d*d+3d-88=0

We add all the numbers together, and all the variables

3d+d*d-88=0

Wy multiply elements

d^2+3d-88=0

a = 1; b = 3; c = -88;
Δ = b2-4ac
Δ = 32-4·1·(-88)
Δ = 361
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{361}=19$
$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(3)-19}{2*1}=\frac{-22}{2}
=-11
$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(3)+19}{2*1}=\frac{16}{2}
=8
$