2/5b+21=b

Solution for 2/5b+21=b equation:

2/5b+21=b

We move all terms to the left:

2/5b+21-(b)=0


Domain of the equation: 5b!=0

b!=0/5

b!=0

b∈R


We add all the numbers together, and all the variables

-1b+2/5b+21=0

We multiply all the terms by the denominator


-1b*5b+21*5b+2=0

Wy multiply elements

-5b^2+105b+2=0

a = -5; b = 105; c = +2;
Δ = b2-4ac
Δ = 1052-4·(-5)·2
Δ = 11065
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(105)-\sqrt{11065}}{2*-5}=\frac{-105-\sqrt{11065}}{-10}
$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(105)+\sqrt{11065}}{2*-5}=\frac{-105+\sqrt{11065}}{-10}
$