Question
Answer
$$(i-1)i=-i-1$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}(i-1)i& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}i^2-i \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}-1-i \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle3}{\textcircled {3}} } }}}-i-1\end{aligned} $$ | |
| ① | $$ \left( \color{blue}{i-1}\right) \cdot i = i^2-i $$ |
| ② | $$ i^2 = -1 $$ |
| ③ | Combine like terms: $$ -i-1 = -i-1 $$ |
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