3x2+x=7.5

Solution for 3x2+x=7.5 equation:

3x^2+x=7.5

We move all terms to the left:

3x^2+x-(7.5)=0

We add all the numbers together, and all the variables

3x^2+x-7.5=0

a = 3; b = 1; c = -7.5;
Δ = b2-4ac
Δ = 12-4·3·(-7.5)
Δ = 91
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{-(1)-\sqrt{91}}{2*3}=\frac{-1-\sqrt{91}}{6}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1)+\sqrt{91}}{2*3}=\frac{-1+\sqrt{91}}{6}
$