Question

NO LINKS OR ELSE YOU'LL BE REPORTED! Only answer if you're very good at Math.

Let u= (5,-12) and c= -3.What is ||cu||?

A: 21

B: 51

C: 39

D: -39​

Answer 1

`=21`

Correct option is A

Explanation:

`-3\left(5-12\right)\\Follow\:the\:PEMDAS\:order\:of\:operations\\\mathrm{Calculate\:within\:parentheses}\:\left(5-12\right)\::\quad -7\\5-12=-7\\=-3\left(-7\right)\\\mathrm{Multiply\:and\:divide\:\left(left\:to\:right\right)}\:-3\left(-7\right)\::\quad 21\\-3\left(-7\right)\\\mathrm{Apply\:rule\:}-a\cdot \left(-b\right)\:=\:a\cdot \:b\\-3\left(-7\right)=3\cdot \:7=21\\=21`

Answer 2

CU=-3(5,-12)

CU=36-15

CU=21

The answer is A=21