Question

Let u = <-5, -3>, v = <-6, -1>. Find -3u + 5v.
@hero @dan815 @nincompoop @mathstudent55 @wio @radar @undeadknight26

Answer 1

HI!!

Answer 2

multiply both entries in \(u\) by \(-3\)
multiply both entries in \(v\) by \(5\)
then add

Answer 3

huh? @misty1212

Answer 4

i don't really know another way to say it

Answer 5

u has two numbers right?

Answer 6

can u show me? @misty1212

Answer 7

multiply each of them by \(-3\)

Answer 8

\[u=<-5,-3>\\
-3u=-3<-5,-3>=<15,9>\]

Answer 9

in other words, multiply each entry by \(-3\)

Answer 10

repeat to find \[5v=5<-6,-1>\]

Answer 11

so its <-30,-5> @misty1212

Answer 12

yes

Answer 13

then add

Answer 14

can u help me with another? @misty1212

Answer 15

did you add them yet?

Answer 16

yes i got <-15,4> @misty1212

Answer 17

oops yes you are right sorry

Answer 18

can u help me with another? @misty1212

Answer 19

ok sure

Answer 20

Find a • b.
a = 4i + 3j, b = -4i + 4j

-4
28
<-16, 12>
<0, 7>

Answer 21

is that a dot between them?

Answer 22

i think it times

Answer 23

i think it means the "dot product"

Answer 24

\[<4,3>\cdot<-4,4>=4\times (-4)+3\times 4\]

Answer 25

it is a number, not a vector

Answer 26

\[-16+12=-4\] in other words

Answer 27

Find the first six terms of the sequence.
a1 = -7, an = 2 • an-1

-7, -14, -12, -10, -8, -6
0, 2, -14, -12, -10, -8
-7, -14, -28, -56, -112, -224
-14, -28, -56, -112, -224, -448

Answer 28

@misty1212

Answer 29

start with \(-7\)

Answer 30

then multiply it by 2 to get the next number

Answer 31

\[-7,-7\times 2,-7\times 2\times 2...\]

Answer 32

so this one
\[ -7, -14, -28, -56, -112, -224\]

Answer 33

Find the standard form of the equation of the parabola with a focus at (0, 4) and a directrix at y = -4.

y = 1 divided by 16x2
y2 = 16x
y2 = 4x
y = 1 divided by 4x2
@misty1212

Answer 34

i would go with the first one
want to check?

Answer 35

http://www.wolframalpha.com/input/?i=parabola+y+%3D+1%2F16x%5E2

Answer 36

yup looks good

Answer 37

Find an explicit rule for the nth term of the sequence.

3, -12, 48, -192, ...

an = 3 • 4n - 1
an = 3 • 4n + 1
an = 3 • (-4)n - 1
an = 3 • (-4)n
@misty1212

Answer 38

see how the signs change?

Answer 39

yes by -4 @misty1212

Answer 40

so only \[a_n=3(-4)^{n-1}\] makes any sense

Answer 41

one last one? @misty1212

Answer 42

kk

Answer 43

Use graphs and tables to find the limit and identify any vertical asymptotes of the function.

Answer 44

? vertical asymptote is where the denominator is zero, so \(x=5\)

Answer 45

what is the limit @misty1212

Answer 46

ooh i see

Answer 47

limit is infinity \(\infty\)

Answer 48

oh no oops

Answer 49

try \(-\infty\)