0=(4x+7)(4x+3)

Solution for 0=(4x+7)(4x+3) equation:

0=(4x+7)(4x+3)

We move all terms to the left:

0-((4x+7)(4x+3))=0

We add all the numbers together, and all the variables

-((4x+7)(4x+3))=0

We multiply parentheses ..

-((+16x^2+12x+28x+21))=0


We calculate terms in parentheses: -((+16x^2+12x+28x+21)), so:

(+16x^2+12x+28x+21)

We get rid of parentheses

16x^2+12x+28x+21

We add all the numbers together, and all the variables

16x^2+40x+21

Back to the equation:

-(16x^2+40x+21)


We get rid of parentheses

-16x^2-40x-21=0

a = -16; b = -40; c = -21;
Δ = b2-4ac
Δ = -402-4·(-16)·(-21)
Δ = 256
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{256}=16$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-40)-16}{2*-16}=\frac{24}{-32}
=-3/4
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-40)+16}{2*-16}=\frac{56}{-32}
=-1+3/4
$