3a^2-2a+5a^2=7a

Solution for 3a^2-2a+5a^2=7a equation:

3a^2-2a+5a^2=7a

We move all terms to the left:

3a^2-2a+5a^2-(7a)=0

We add all the numbers together, and all the variables

8a^2-9a=0

a = 8; b = -9; c = 0;
Δ = b2-4ac
Δ = -92-4·8·0
Δ = 81
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{81}=9$
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-9)-9}{2*8}=\frac{0}{16}
=0
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-9)+9}{2*8}=\frac{18}{16}
=1+1/8
$