Tap the blue circles to see an explanation.
| $$ \begin{aligned}4 \cdot \frac{u}{25}u& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}\frac{4u}{25}u \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}\frac{4u^2}{25}\end{aligned} $$ | |
| ① | Multiply $4$ by $ \dfrac{u}{25} $ to get $ \dfrac{ 4u }{ 25 } $. Step 1: Write $ 4 $ as a fraction by putting $ \color{red}{1} $ in the denominator. Step 2: Multiply numerators and denominators. Step 3: Simplify numerator and denominator. $$ \begin{aligned} 4 \cdot \frac{u}{25} & \xlongequal{\text{Step 1}} \frac{4}{\color{red}{1}} \cdot \frac{u}{25} \xlongequal{\text{Step 2}} \frac{ 4 \cdot u }{ 1 \cdot 25 } = \\[1ex] & \xlongequal{\text{Step 3}} \frac{ 4u }{ 25 } \end{aligned} $$ |
| ② | Multiply $ \dfrac{4u}{25} $ by $ u $ to get $ \dfrac{ 4u^2 }{ 25 } $. Step 1: Write $ u $ as a fraction by putting $ \color{red}{ 1 } $ in the denominator. Step 2: Multiply numerators and denominators. Step 3: Simplify numerator and denominator. $$ \begin{aligned} \frac{4u}{25} \cdot u & \xlongequal{\text{Step 1}} \frac{4u}{25} \cdot \frac{u}{\color{red}{1}} \xlongequal{\text{Step 2}} \frac{ 4u \cdot u }{ 25 \cdot 1 } = \\[1ex] & \xlongequal{\text{Step 3}} \frac{ 4u^2 }{ 25 } \end{aligned} $$ |