Question

If |8i-j|=|7i+kj| (vectors), find two possible values for k belongs to R. Answers: +4, -4. How?

Answer 1

becasue it is asking for the length of the vectors to be equal

Answer 2

@amistre64 I need step by step how to do it... I undestand why it is +4 and -4

Answer 3

\[8^2+1^2=7^2+k^2\]
\[8^2+1^2-7^2=k^2\]

Answer 4

Oooooooooh my God! It's that simple! Thank you very much!

Answer 5

youre welcome