49=(x+11)(3x-7)

Solution for 49=(x+11)(3x-7) equation:

49=(x+11)(3x-7)

We move all terms to the left:

49-((x+11)(3x-7))=0

We multiply parentheses ..

-((+3x^2-7x+33x-77))+49=0


We calculate terms in parentheses: -((+3x^2-7x+33x-77)), so:

(+3x^2-7x+33x-77)

We get rid of parentheses

3x^2-7x+33x-77

We add all the numbers together, and all the variables

3x^2+26x-77

Back to the equation:

-(3x^2+26x-77)


We get rid of parentheses

-3x^2-26x+77+49=0

We add all the numbers together, and all the variables

-3x^2-26x+126=0

a = -3; b = -26; c = +126;
Δ = b2-4ac
Δ = -262-4·(-3)·126
Δ = 2188
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{2188}=\sqrt{4*547}=\sqrt{4}*\sqrt{547}=2\sqrt{547}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-26)-2\sqrt{547}}{2*-3}=\frac{26-2\sqrt{547}}{-6}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-26)+2\sqrt{547}}{2*-3}=\frac{26+2\sqrt{547}}{-6}
$