7b^2=42b

Solution for 7b^2=42b equation:

7b^2=42b

We move all terms to the left:

7b^2-(42b)=0

a = 7; b = -42; c = 0;
Δ = b2-4ac
Δ = -422-4·7·0
Δ = 1764
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1764}=42$
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-42)-42}{2*7}=\frac{0}{14}
=0
$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-42)+42}{2*7}=\frac{84}{14}
=6
$