Simplify to a plus bi form. (5-10i)2?

Answer 1

I assume you mean (5 - 10i) squared; just multiply it by itself, in other words:(5 - 10i)(5 - 10i)

To multiply two binomials, you need to multiply each term on the left by each term on the right (four terms in total). Remember that i squared = -1.

Answer 2

(5 - 10i)²

= (5 - 10i)(5 - 10i)

= 5² - 5×10i - 5×10i + (10i)²

= 25 - 100i + 100×(√-1)²

= 25 - 100i - 100

= -75 - 100i