28u2-47=-40

Solution for 28u2-47=-40 equation:

28u^2-47=-40

We move all terms to the left:

28u^2-47-(-40)=0

We add all the numbers together, and all the variables

28u^2-7=0

a = 28; b = 0; c = -7;
Δ = b2-4ac
Δ = 02-4·28·(-7)
Δ = 784
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$u_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$u_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{784}=28$
$u_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-28}{2*28}=\frac{-28}{56}
=-1/2
$
$u_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+28}{2*28}=\frac{28}{56}
=1/2
$