For vectors u=-6i +2k and v=7i-4j, find (-3u)*v. a) -450 b) -50 c) 108 d) 150 i know how to do these problems, but i am stuck on this question, because i keep finding the answer 118. i know you change -6i+2j to (-6,2) and 7i-4j to (7,-4) and then plug them into the equation but i don't know what i am doing wrong.

step-by-step explanation:

the original amount doesn't ''re just looking for the time it takes for 1/2 of the substance to we have

(1/2) =)     take the ln   of both sides

ln (1/2)   = )   and we can write

ln(1/2) = ) lne     and lne   = 1     so we have

ln(1/2) = -.1092t     divide both sides by -.1092

t = ln(1/2)/-.1092 = about 6.347 days = about 6.3 days (rounded)