A=-3x(4x-5)

Solution for A=-3x(4x-5) equation:

=-3A(4A-5)

We move all terms to the left:

-(-3A(4A-5))=0


We calculate terms in parentheses: -(-3A(4A-5)), so:

-3A(4A-5)

We multiply parentheses

-12A^2+15A

Back to the equation:

-(-12A^2+15A)


We get rid of parentheses

12A^2-15A=0

a = 12; b = -15; c = 0;
Δ = b2-4ac
Δ = -152-4·12·0
Δ = 225
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$A_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$A_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{225}=15$
$A_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-15)-15}{2*12}=\frac{0}{24}
=0
$
$A_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-15)+15}{2*12}=\frac{30}{24}
=1+1/4
$