Express the following complex numbers in the standard form a + i b : (

1.	Express the following complex numbers in the standard form a + i b : (1 + i) (1 + 2i)
Answer» ⇒ a+ib = (1+i)(1+2i) ⇒ a+ib = 1(1+2i)+i(1+2i) ⇒ a+ib = 1+2i+i+2i² We know that i²=-1 ⇒ a+ib = 1+3i+2(-1) ⇒ a+ib = 1+3i-2 ⇒ a+ib=-1+3i ∴ The values of a, b are -1, 3.

Express the following complex numbers in the standard form a + i b : (1 + i) (1 + 2i)

Answer»

⇒ a+ib = (1+i)(1+2i)

⇒ a+ib = 1(1+2i)+i(1+2i)

⇒ a+ib = 1+2i+i+2i²

We know that i²=-1

⇒ a+ib = 1+3i+2(-1)

⇒ a+ib = 1+3i-2

⇒ a+ib=-1+3i

∴ The values of a, b are -1, 3.