| $$ \begin{aligned}\frac{-16a^3-4}{2}a& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}\frac{-16a^4-4a}{2}\end{aligned} $$ | |
| ① | Multiply $ \dfrac{-16a^3-4}{2} $ by $ a $ to get $ \dfrac{ -16a^4-4a }{ 2 } $. Step 1: Write $ a $ as a fraction by putting $ \color{red}{ 1 } $ in the denominator. Step 2: Multiply numerators and denominators. Step 3: Simplify numerator and denominator. $$ \begin{aligned} \frac{-16a^3-4}{2} \cdot a & \xlongequal{\text{Step 1}} \frac{-16a^3-4}{2} \cdot \frac{a}{\color{red}{1}} \xlongequal{\text{Step 2}} \frac{ \left( -16a^3-4 \right) \cdot a }{ 2 \cdot 1 } = \\[1ex] & \xlongequal{\text{Step 3}} \frac{ -16a^4-4a }{ 2 } \end{aligned} $$ |