Engineering Board Exam Reviewer · Complex Numbers: Operations · easy

Simplify 5+5i/1-2i.

1. 3 - i
2. -1 + 3i
3. -1 - 3i
4. -5 + 15i

Answer

B. -1 + 3i

Solution

Multiply by the conjugate: (5+5i)(1+2i)/(1-2i)(1+2i)=5+10i+5i+10i2/1+4=-5+15i/5=-1+3i.

More Complex Numbers: Operations questions

1. Simplify (3+2i)(4-5i).
2. Simplify: i2001
3. Simplify: i15+i18
4. Add: (3+5i)+(2-7i)
5. Multiply: (4+3i)(2-i)
6. Divide: 3+4i/1-2i
7. Find the absolute value (modulus) of 5-12i.
8. Find the complex conjugate of 6-8i, then multiply it by the original number.
9. Simplify: (2+3i)2
10. Find the square roots of 3+4i.

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