3x^2-1=-7x

Solution for 3x^2-1=-7x equation:

3x^2-1=-7x

We move all terms to the left:

3x^2-1-(-7x)=0

We get rid of parentheses

3x^2+7x-1=0

a = 3; b = 7; c = -1;
Δ = b2-4ac
Δ = 72-4·3·(-1)
Δ = 61
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(7)-\sqrt{61}}{2*3}=\frac{-7-\sqrt{61}}{6}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(7)+\sqrt{61}}{2*3}=\frac{-7+\sqrt{61}}{6}
$