45x^2+16x=0.8

Solution for 45x^2+16x=0.8 equation:

45x^2+16x=0.8

We move all terms to the left:

45x^2+16x-(0.8)=0

We add all the numbers together, and all the variables

45x^2+16x-0.8=0

a = 45; b = 16; c = -0.8;
Δ = b2-4ac
Δ = 162-4·45·(-0.8)
Δ = 400
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{400}=20$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(16)-20}{2*45}=\frac{-36}{90}
=-2/5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(16)+20}{2*45}=\frac{4}{90}
=2/45
$