4c^2=-7c

Solution for 4c^2=-7c equation:

4c^2=-7c

We move all terms to the left:

4c^2-(-7c)=0

We get rid of parentheses

4c^2+7c=0

a = 4; b = 7; c = 0;
Δ = b2-4ac
Δ = 72-4·4·0
Δ = 49
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$c_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$c_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{49}=7$
$c_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(7)-7}{2*4}=\frac{-14}{8}
=-1+3/4
$
$c_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(7)+7}{2*4}=\frac{0}{8}
=0
$