(15x+42)(x+8=9)

Solution for (15x+42)(x+8=9) equation:

(15x+42)(x+8=9)

We move all terms to the left:

(15x+42)(x+8-(9))=0

We add all the numbers together, and all the variables

(15x+42)(x-1)=0

We multiply parentheses ..

(+15x^2-15x+42x-42)=0

We get rid of parentheses

15x^2-15x+42x-42=0

We add all the numbers together, and all the variables

15x^2+27x-42=0

a = 15; b = 27; c = -42;
Δ = b2-4ac
Δ = 272-4·15·(-42)
Δ = 3249
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{3249}=57$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(27)-57}{2*15}=\frac{-84}{30}
=-2+4/5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(27)+57}{2*15}=\frac{30}{30}
=1
$