X=7/5x-21

Solution for X=7/5x-21 equation:

X=7/5X-21

We move all terms to the left:

X-(7/5X-21)=0


Domain of the equation: 5X-21)!=0

X∈R


We get rid of parentheses

X-7/5X+21=0

We multiply all the terms by the denominator


X*5X+21*5X-7=0

Wy multiply elements

5X^2+105X-7=0

a = 5; b = 105; c = -7;
Δ = b2-4ac
Δ = 1052-4·5·(-7)
Δ = 11165
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(105)-\sqrt{11165}}{2*5}=\frac{-105-\sqrt{11165}}{10}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(105)+\sqrt{11165}}{2*5}=\frac{-105+\sqrt{11165}}{10}
$