imaginary and complex numbers

What does i⁴ = ?

What does i² = ?

Simplify the expression to a + bi form: $\left(2-i\right)-\left(-4+8i\right)$  

• 6 - 9i

• -2 + 7i

• 6 + 7i

• -2 - 9i

Simplify.

• A

• B

• C

• D

Simplify the expression to a + bi form: $\left(3+i\right)+\left(-12-9i\right)$  

• 15 - 8i

• -9 + 10i

• 15 + 10i

• - 9 - 8i

Multiply:
(2-5i)(2+5i)

• 29
• 4 - 25i
• 25 - 10i
• -21

Simplify this expression

• 12

• 7i

• -12

• -7i

 $If\ x^{2\ }=\ -36,\ then\ x\ =\$  

Write $\sqrt{-10}$ in simplest radical form.  

•  $-i\sqrt{10}$  

•  $i\sqrt{10}$  

•  $-\sqrt{5}\sqrt{2}$  

•  $\sqrt{5}\sqrt{2}\sqrt{-1}$  

Calculate:
(4 − 7i) − (-3 + 6i)

• 7 − 13i
• 7 − i 
• 1 − 13i
• 1 − i