2y=5y(-21/2)

Solution for 2y=5y(-21/2) equation:

2y=5y(-21/2)

We move all terms to the left:

2y-(5y(-21/2))=0

We multiply all the terms by the denominator


2y*2))-(5y(-21=0

Wy multiply elements

4y^2-21=0

a = 4; b = 0; c = -21;
Δ = b2-4ac
Δ = 02-4·4·(-21)
Δ = 336
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{336}=\sqrt{16*21}=\sqrt{16}*\sqrt{21}=4\sqrt{21}$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-4\sqrt{21}}{2*4}=\frac{0-4\sqrt{21}}{8}
=-\frac{4\sqrt{21}}{8}
=-\frac{\sqrt{21}}{2}
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+4\sqrt{21}}{2*4}=\frac{0+4\sqrt{21}}{8}
=\frac{4\sqrt{21}}{8}
=\frac{\sqrt{21}}{2}
$