-42=7b^2-385

Solution for -42=7b^2-385 equation:

-42=7b^2-385

We move all terms to the left:

-42-(7b^2-385)=0

We get rid of parentheses

-7b^2+385-42=0

We add all the numbers together, and all the variables

-7b^2+343=0

a = -7; b = 0; c = +343;
Δ = b2-4ac
Δ = 02-4·(-7)·343
Δ = 9604
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{9604}=98$
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-98}{2*-7}=\frac{-98}{-14}
=+7
$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+98}{2*-7}=\frac{98}{-14}
=-7
$