(3b+8)(7b-6)=0

Solution for (3b+8)(7b-6)=0 equation:

(3b+8)(7b-6)=0

We multiply parentheses ..

(+21b^2-18b+56b-48)=0

We get rid of parentheses

21b^2-18b+56b-48=0

We add all the numbers together, and all the variables

21b^2+38b-48=0

a = 21; b = 38; c = -48;
Δ = b2-4ac
Δ = 382-4·21·(-48)
Δ = 5476
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{5476}=74$
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(38)-74}{2*21}=\frac{-112}{42}
=-2+2/3
$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(38)+74}{2*21}=\frac{36}{42}
=6/7
$