(3x-8)(7x+10)=

Solution for (3x-8)(7x+10)= equation:

(3x-8)(7x+10)=

We move all terms to the left:

(3x-8)(7x+10)-()=0

We add all the numbers together, and all the variables

(3x-8)(7x+10)=0

We multiply parentheses ..

(+21x^2+30x-56x-80)=0

We get rid of parentheses

21x^2+30x-56x-80=0

We add all the numbers together, and all the variables

21x^2-26x-80=0

a = 21; b = -26; c = -80;
Δ = b2-4ac
Δ = -262-4·21·(-80)
Δ = 7396
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{7396}=86$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-26)-86}{2*21}=\frac{-60}{42}
=-1+3/7
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-26)+86}{2*21}=\frac{112}{42}
=2+2/3
$