QUESTION IMAGE
Question
$i^9 = $
$i^2 = $
$-sqrt{-100}$
$-7i = $
1. Solve \(i^9\)
Step1: Recall \(i\) powers cycle
The imaginary unit \(i\) has a cycle: \(i^1 = i\), \(i^2=-1\), \(i^3 = -i\), \(i^4 = 1\), and then repeats every 4. So we can express \(i^9\) as \(i^{4\times2 + 1}\).
Step2: Simplify using exponent rules
Using \(a^{m+n}=a^m\times a^n\), \(i^{4\times2+1}=(i^4)^2\times i^1\). Since \(i^4 = 1\), then \((1)^2\times i=i\).
Step1: Recall definition of \(i\)
By definition, the imaginary unit \(i=\sqrt{-1}\), so \(i^2 = (\sqrt{-1})^2=-1\).
Step1: Simplify square root of negative number
We know that \(\sqrt{-a}=i\sqrt{a}\) for \(a>0\). So \(\sqrt{-100}=i\sqrt{100}\).
Step2: Calculate \(\sqrt{100}\) and simplify
\(\sqrt{100} = 10\), so \(\sqrt{-100}=10i\). Then \(-\sqrt{-100}=- 10i\).
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\(i^9 = i\)