F(x)=28/x+7

Solution for F(x)=28/x+7 equation:

(F)=28/F+7

We move all terms to the left:

(F)-(28/F+7)=0


Domain of the equation: F+7)!=0

F∈R


We get rid of parentheses

F-28/F-7=0

We multiply all the terms by the denominator


F*F-7*F-28=0

We add all the numbers together, and all the variables

-7F+F*F-28=0

Wy multiply elements

F^2-7F-28=0

a = 1; b = -7; c = -28;
Δ = b2-4ac
Δ = -72-4·1·(-28)
Δ = 161
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$F_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$F_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$F_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-7)-\sqrt{161}}{2*1}=\frac{7-\sqrt{161}}{2}
$
$F_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-7)+\sqrt{161}}{2*1}=\frac{7+\sqrt{161}}{2}
$