5=1.4x^2

Solution for 5=1.4x^2 equation:

5=1.4x^2

We move all terms to the left:

5-(1.4x^2)=0

We get rid of parentheses

-1.4x^2+5=0

a = -1.4; b = 0; c = +5;
Δ = b2-4ac
Δ = 02-4·(-1.4)·5
Δ = 28
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:

$\sqrt{\Delta}=\sqrt{28}=\sqrt{4*7}=\sqrt{4}*\sqrt{7}=2\sqrt{7}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-2\sqrt{7}}{2*-1.4}=\frac{0-2\sqrt{7}}{-2.8}
=-\frac{2\sqrt{7}}{-2.8}
=-\frac{\sqrt{7}}{-1.4}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+2\sqrt{7}}{2*-1.4}=\frac{0+2\sqrt{7}}{-2.8}
=\frac{2\sqrt{7}}{-2.8}
=\frac{\sqrt{7}}{-1.4}
$