Question

Write the expression -5i(1 + 3i) as a complex number in standard form

Answer 1

you just have to expand it I guess.
\(\large\color{blue}{ -5i(1 + 3i) }\)
\(\large\color{blue}{ ~~~~~~~~~~~~~~~~~~~~~~=(-5i)(1) + (-5i)(3i) }\)\(\LARGE\color{white}{ \rm │ }\)
\(\large\color{blue}{ ~~~~~~~~~~~~~~~~~~~~~~=-5i+ (-5i)(3i) }\)\(\LARGE\color{white}{ \rm │ }\)
\(\large\color{blue}{ ~~~~~~~~~~~~~~~~~~~~~~=-5i+ (-15i^2) }\)\(\LARGE\color{white}{ \rm │ }\)
\(\large\color{blue}{ ~~~~~~~~~~~~~~~~~~~~~~=-5i+ (-15[-1]~) }\)\(\LARGE\color{white}{ \rm │ }\)
\(\large\color{blue}{ ~~~~~~~~~~~~~~~~~~~~~~=-5i+ (15) }\)\(\LARGE\color{white}{ \rm │ }\)
\(\large\color{blue}{ ~~~~~~~~~~~~~~~~~~~~~~=-5i+ 15 }\)\(\LARGE\color{white}{ \rm │ }\)
\(\large\color{blue}{ ~~~~~~~~~~~~~~~~~~~~~~=~~15-5i. }\)\(\LARGE\color{white}{ \rm │ }\) that's all.

Answer 2

thank you!! @SolomonZelman

Answer 3

Anytime:)