Complex Imaginary Numbers

Calculate (multiply):
(1 − 2i)(6 + 5i)

• 16 − 7i

• -16 + 7i

• -16 − 7i

• 16 + 7i

Calculate:
(4 − 7i) − (-3 + 6i)

• 7 − 13i

• 7 − i 

• 1 − 13i

• 1 − i 

Calculate: 
-12i + 7i

• 19i

• -19i

• 5i

• -5i

Calculate:
-4 (13 + 5i) 

• -52 − 20i

• 9 + i

• 17 − 20i

• -52 + 20i

What letter usually represent imaginary number?

• a

• i

• j

• x

• e

Answer explanation

6i (-5 + 10i)

• -30i + 60i²

• 30i − 16i²

• 11i + 60i²

• -11i²+ 16i

Calculate (multiply):
 (4 + 3i)(4 − 3i)

• 16 − 9i²

• 25

• 7

• 8 − 6i

Simplify: √-25

• 5

• -5

• 5i

• -5i

Simplify: √-100

• 10i

• -10i

• 10

• -10

Find the conjugate of:
5 + 7i

• 5 − 7i

• -5 − 7i

• -5 + 7i