So I am learning Quadratic Equations and I have learned about the Formulas for calculating the Delta $(\Delta)$ and $x_1$, $x_2$.
I have this equation $$x^2 - 10x + 15 = 0$$ and I've tried to do my best but it turns out that I have the wrong result on $x_2$ according to cymath.com.
Could someone explain what I've done wrong ?
$x^2-10x+15=0$
$\Delta = b^2-4ac=100-4\times 15=100-60$
$\Delta = 40$
$\Delta > 0$
$x=\dfrac{-(b)\pm\sqrt\Delta}{2a}$
$x_1=\dfrac{-(-10)+\sqrt\Delta}{2}=\dfrac{10+\sqrt\Delta}{2} = 8.16$
$x_2=\dfrac{-(-10)-\sqrt\Delta}{2}=\dfrac{10-\sqrt\Delta}{2} = 3.67$
You didn't divide by $2$ $$10-\sqrt{40}\approx 3.67$$ Now you were asked for $$\frac{10-\sqrt{40}}{2}\approx\frac{3.67}{2}=1.835$$