Question

How do you simplify (4-5i)(4+5i) and write the complex number in standard form?

Answer 1

Answer:

16-25i^2

a^2-b^2=(a+b) (a-b)

4^2-5i^2

=16-25i^2

Answer 2

Answer:

41

Step-by-step explanation:

(4-5i)(4+5i)=4² - (5i)² .......... (using the identity (a+b)(a-b)=a² - b²)

=16-25( i )²

But i² = -1

∴ (4-5i)(4+5i)=16+25=41