Question
Find roots of polynomial $$ p(x) = 15x^2+18x $$
Answer
The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 0\\[1 em]x_2 &= -\dfrac{ 6 }{ 5 } \end{aligned} $$Explanation
Step 1:
Factor out $ \color{blue}{ 3x }$ from $ 15x^2+18x $ and solve two separate equations:
$$ \begin{aligned} 15x^2+18x & = 0\\[1 em] \color{blue}{ 3x }\cdot ( 5x+6 ) & = 0 \\[1 em] \color{blue}{ 3x = 0} ~~ \text{or} ~~ 5x+6 & = 0 \end{aligned} $$One solution is $ \color{blue}{ x = 0 } $. Use second equation to find the remaining roots.
Step 2:
To find the second zero, solve equation $ 5x+6 = 0 $
$$ \begin{aligned} 5x+6 & = 0 \\[1 em] 5 \cdot x & = -6 \\[1 em] x & = - \frac{ 6 }{ 5 } \end{aligned} $$This page was created using
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