Let's solve each problem step by step, simplifying radicals using imaginary numbers and performing operations with complex numbers.
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Key Concepts:
- $\sqrt{-a} = \sqrt{a} \cdot i$, where $i = \sqrt{-1}$
- For complex numbers:
$(a + bi) + (c + di) = (a + c) + (b + d)i$
$(a + bi) - (c + di) = (a - c) + (b - d)i$
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Problem 1: $\sqrt{-12}$
$$
\sqrt{-12} = \sqrt{12} \cdot i = \sqrt{4 \cdot 3} \cdot i = 2\sqrt{3}i
$$
✔ Answer: $2\sqrt{3}i$
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Problem 2: $\sqrt{-128}$
$$
\sqrt{-128} = \sqrt{128} \cdot i = \sqrt{64 \cdot 2} \cdot i = 8\sqrt{2}i
$$
✔ Answer: $8\sqrt{2}i$
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Problem 3: $\sqrt{-512}$
$$
\sqrt{-512} = \sqrt{512} \cdot i = \sqrt{256 \cdot 2} \cdot i = 16\sqrt{2}i
$$
✔ Answer: $16\sqrt{2}i$
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Problem 4: $\sqrt{-36}$
$$
\sqrt{-36} = \sqrt{36} \cdot i = 6i
$$
✔ Answer: $6i$
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Problem 5: $\sqrt{-147}$
$$
\sqrt{-147} = \sqrt{147} \cdot i = \sqrt{49 \cdot 3} \cdot i = 7\sqrt{3}i
$$
✔ Answer: $7\sqrt{3}i$
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Problem 6: $(-5 - 4i) + (8 - 7i)$
Add real parts and imaginary parts:
- Real: $-5 + 8 = 3$
- Imaginary: $-4i - 7i = -11i$
✔ Answer: $3 - 11i$
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Problem 7: $(-3 - 8i) - (6i + 3i)$
Wait — the second term is written as $(6i + 3i)$, which is just $9i$. But let’s check:
It says: $(-3 - 8i) - (6i + 3i)$ → that’s $(-3 - 8i) - 9i$
Now subtract:
- Real: $-3$
- Imaginary: $-8i - 9i = -17i$
✔ Answer: $-3 - 17i$
> Note: If the problem meant $(-3 - 8i) - (6 + 3i)$, it would be different. But as written, it's $(6i + 3i)$, so we interpret it as $9i$. However, this seems like a typo. Let's double-check.
But looking again:
"(-3 - 8i) - (6i + 3i)" → this is likely intended to be subtraction of two complex numbers. But $(6i + 3i)$ is not standard form. It's probably meant to be $(6 + 3i)$ or $(6i + 3i)$ as $9i$. But if it's truly $(6i + 3i)$, then it's $9i$, so:
$$
(-3 - 8i) - 9i = -3 - 17i
$$
✔ Answer: $-3 - 17i$
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Problem 8: $(-4 - 5i) - (4 + 6i)$
Subtract:
- Real: $-4 - 4 = -8$
- Imaginary: $-5i - 6i = -11i$
✔ Answer: $-8 - 11i$
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Problem 9: $(-6 - 7i) + (2 + 6i)$
Add:
- Real: $-6 + 2 = -4$
- Imaginary: $-7i + 6i = -i$
✔ Answer: $-4 - i$
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Problem 10: $(-5 - 4i) + (8 - 7i)$
This is
identical to Problem 6.
- Real: $-5 + 8 = 3$
- Imaginary: $-4i - 7i = -11i$
✔ Answer: $3 - 11i$
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✔ Final Answers:
| Problem | Answer |
|--------|--------|
| 1 | $2\sqrt{3}i$ |
| 2 | $8\sqrt{2}i$ |
| 3 | $16\sqrt{2}i$ |
| 4 | $6i$ |
| 5 | $7\sqrt{3}i$ |
| 6 | $3 - 11i$ |
| 7 | $-3 - 17i$ |
| 8 | $-8 - 11i$ |
| 9 | $-4 - i$ |
| 10 | $3 - 11i$ |
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Parent Tip: Review the logic above to help your child master the concept of simplifying radicals worksheet pdf.