4y^2-40y-21=-

Solution for 4y^2-40y-21=- equation:

4y^2-40y-21=-

We move all terms to the left:

4y^2-40y-21-(-)=0

We add all the numbers together, and all the variables

4y^2-40y-21-0=0

We add all the numbers together, and all the variables

4y^2-40y-21=0

a = 4; b = -40; c = -21;
Δ = b2-4ac
Δ = -402-4·4·(-21)
Δ = 1936
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1936}=44$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-40)-44}{2*4}=\frac{-4}{8}
=-1/2
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-40)+44}{2*4}=\frac{84}{8}
=10+1/2
$