4/5x+2x=28

Solution for 4/5x+2x=28 equation:

4/5x+2x=28

We move all terms to the left:

4/5x+2x-(28)=0


Domain of the equation: 5x!=0

x!=0/5

x!=0

x∈R


We add all the numbers together, and all the variables

2x+4/5x-28=0

We multiply all the terms by the denominator


2x*5x-28*5x+4=0

Wy multiply elements

10x^2-140x+4=0

a = 10; b = -140; c = +4;
Δ = b2-4ac
Δ = -1402-4·10·4
Δ = 19440
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{19440}=\sqrt{1296*15}=\sqrt{1296}*\sqrt{15}=36\sqrt{15}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-140)-36\sqrt{15}}{2*10}=\frac{140-36\sqrt{15}}{20}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-140)+36\sqrt{15}}{2*10}=\frac{140+36\sqrt{15}}{20}
$