10x^2+7=987

Solution for 10x^2+7=987 equation:

10x^2+7=987

We move all terms to the left:

10x^2+7-(987)=0

We add all the numbers together, and all the variables

10x^2-980=0

a = 10; b = 0; c = -980;
Δ = b2-4ac
Δ = 02-4·10·(-980)
Δ = 39200
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:

$\sqrt{\Delta}=\sqrt{39200}=\sqrt{19600*2}=\sqrt{19600}*\sqrt{2}=140\sqrt{2}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-140\sqrt{2}}{2*10}=\frac{0-140\sqrt{2}}{20}
=-\frac{140\sqrt{2}}{20}
=-7\sqrt{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+140\sqrt{2}}{2*10}=\frac{0+140\sqrt{2}}{20}
=\frac{140\sqrt{2}}{20}
=7\sqrt{2}
$