7a^2=2,5^2

Solution for 7a^2=2,5^2 equation:

7a^2=2.5^2

We move all terms to the left:

7a^2-(2.5^2)=0

We add all the numbers together, and all the variables

7a^2-6.25=0

a = 7; b = 0; c = -6.25;
Δ = b2-4ac
Δ = 02-4·7·(-6.25)
Δ = 175
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{175}=\sqrt{25*7}=\sqrt{25}*\sqrt{7}=5\sqrt{7}$
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-5\sqrt{7}}{2*7}=\frac{0-5\sqrt{7}}{14}
=-\frac{5\sqrt{7}}{14}
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+5\sqrt{7}}{2*7}=\frac{0+5\sqrt{7}}{14}
=\frac{5\sqrt{7}}{14}
$