Complex number arithmetic Quiz

1. Find $(2+3i)(4-i)$.

• A. $8-3i$
• B. $5+2i$
• C. $5+10i$
• D. $11+10i$

2. What are the real and imaginary parts of $z=-5+7i$?

• A. Real part $7$, imaginary part $-5$
• B. Real part $-5$, imaginary part $7$
• C. Real part $-5$, imaginary part $7i$
• D. Real part $5$, imaginary part $7$

3. Solve $z^2+4z+20=0$.

• A. $-2\pm4i$
• B. $2\pm4i$
• C. $-2\pm2i$
• D. $-4\pm4i$

4. Simplify $\frac{1+i}{1-i}$.

• A. $1$
• B. $-i$
• C. $i$
• D. $2i$

5. Given $(a+bi)(1+i)=3+i$ with $a,b$ real, find $a+bi$.

• A. $2+i$
• B. $2-i$
• C. $1-2i$
• D. $-1+2i$