Tap the blue circles to see an explanation.
$$ \begin{aligned}3x(2x-5)(2x-5)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}(6x^2-15x)(2x-5) \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}12x^3-30x^2-30x^2+75x \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle3}{\textcircled {3}} } }}}12x^3-60x^2+75x\end{aligned} $$ | |
① | Multiply $ \color{blue}{3x} $ by $ \left( 2x-5\right) $ $$ \color{blue}{3x} \cdot \left( 2x-5\right) = 6x^2-15x $$ |
② | Multiply each term of $ \left( \color{blue}{6x^2-15x}\right) $ by each term in $ \left( 2x-5\right) $. $$ \left( \color{blue}{6x^2-15x}\right) \cdot \left( 2x-5\right) = 12x^3-30x^2-30x^2+75x $$ |
③ | Combine like terms: $$ 12x^3 \color{blue}{-30x^2} \color{blue}{-30x^2} +75x = 12x^3 \color{blue}{-60x^2} +75x $$ |