9x^2/5=4

Solution for 9x^2/5=4 equation:

9x^2/5=4

We move all terms to the left:

9x^2/5-(4)=0

We multiply all the terms by the denominator


9x^2-4*5=0

We add all the numbers together, and all the variables

9x^2-20=0

a = 9; b = 0; c = -20;
Δ = b2-4ac
Δ = 02-4·9·(-20)
Δ = 720
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:

$\sqrt{\Delta}=\sqrt{720}=\sqrt{144*5}=\sqrt{144}*\sqrt{5}=12\sqrt{5}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-12\sqrt{5}}{2*9}=\frac{0-12\sqrt{5}}{18}
=-\frac{12\sqrt{5}}{18}
=-\frac{2\sqrt{5}}{3}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+12\sqrt{5}}{2*9}=\frac{0+12\sqrt{5}}{18}
=\frac{12\sqrt{5}}{18}
=\frac{2\sqrt{5}}{3}
$