Find roots of polynomial $$ p(x) = -15x^2+90x $$

The roots of polynomial $ p(x) $ are:

$$ \begin{aligned}x_1 &= 0\\[1 em]x_2 &= 6 \end{aligned} $$

Step 1:

Factor out $ \color{blue}{ -15x }$ from $ -15x^2+90x $ and solve two separate equations:

$$ \begin{aligned} -15x^2+90x & = 0\\[1 em] \color{blue}{ -15x }\cdot ( x-6 ) & = 0 \\[1 em] \color{blue}{ -15x = 0} ~~ \text{or} ~~ x-6 & = 0 \end{aligned} $$

One solution is $ \color{blue}{ x = 0 } $. Use second equation to find the remaining roots.

Step 2:

To find the second zero, solve equation $ x-6 = 0 $

$$ \begin{aligned} x-6 & = 0 \\[1 em] x & = 6 \end{aligned} $$

Polynomial Roots Calculator