Understanding and using complex number notation

What number does i represent?

•  $\sqrt{-1}$  

• -1

What does i² = ?

Simplify

• 10

• -10

• 10i

• -10i

 $\sqrt{-1}$  =?

• +1

• 0

• i

• -1

 $\sqrt{-144}$  

• 12

• -12

• 72

• undefined

i² equals...

• 1

• -1

• -i

• 0

• -12

• -15

• -16

• -14

Evaluate:

• 20

• -20

• 20 and -20

• undefined

Answer explanation

Any square root of a negative number is undefined.

• 1

• -1

9k² = -225

• 5

• 5i

• 5i, -5i

• -5, 5