Number systems

Which of these is a rational number?

• 1 pi
• 2 The square root of 5
• 3 0.75
• 4 The square root of 3

i to the power 4 equals:

• 1 i
• 2 -1
• 3 1
• 4 -i

(1 + i)(1 - i) equals:

• 1 -2
• 2 0
• 3 2
• 4 1 - i²

The modulus of 3 + 4i is:

• 1 5
• 2 1
• 3 25
• 4 7

The multiplicative inverse of 2 + i is:

• 1 1 / 2
• 2 (2 + i) / 5
• 3 (2 - i) / 5
• 4 2 - i

The conjugate of 5 - 2i is:

• 1 -5 + 2i
• 2 -5 - 2i
• 3 2 - 5i
• 4 5 + 2i

The value of i³ is:

• 1 1
• 2 -i
• 3 -1
• 4 i

The modulus of -3 + 4i is:

• 1 7
• 2 25
• 3 1
• 4 5