Question

Can Some one check my Pre calc Answers?

Answer 1

Ok, can you show them to us?

Answer 2

Welcome to OpenStudy @ASDFGHJKLLKJHGFDSAa , hope your experience here is Fantastic! If you haven't yet please take the time and look over our Code of conduct http://openstudy.com/code-of-conduct
Feel free to message me anytime you need help.

Answer 3

@sleepyjess

Answer 4

oohhhh vectors, noooo
@ganeshie8 should be able to help

Answer 5

lol okayy

Answer 6

i think i can help :D

Answer 7

Is that correct?

Answer 8

yes

Answer 9

Really ? I guessed it.

Answer 10

oh you guessed well let me tell you why

Answer 11

alright

Answer 12

The vector equation of a line is simply:

r = p + ta

where r, p, a and are vectors and t is some constant. Here, p is the point that the line passes through and a represents a vector than r is parallel to. So, it's easy now. The vector equation is obviously:

r = (-1,6) + t (3,-1)

Which just means r passes through (-1,6) and is parallel to (3,-1) .

Answer 13

ohhh okay thanks! I have two more , could you help??

Answer 14

um sure :D

Answer 15

x = 9t+2 --> t = (x-2)/9
y = -6t+9 --> t = (9-y)/6

then : (x-2)/9 = (9-y)/6

6x-12 = 81-9y
9y = -6x + 93
y = (-2/3)x + 31/3

Answer 16

Thankssss it makes sense now!

Answer 17

one more

Answer 18

omg sorry i forgot about this D; @ASDFGHJKLLKJHGFDSAa you still there

Answer 19

yeahh lol its okay

Answer 20

You said: check, hence, what is your choice?

Answer 21

i dont know how to graph this, this site could be helpful to you
https://www.desmos.com/calculator

Answer 22

Okay , And @Loser66 my guess would have to be the first graph

Answer 23

nope,
you need turn the parametric equations to Euclidean one
that is solve for t, let them equal to get y = something respect to x
then look at the graph, which matches your expression
Now, first off, multiply the first equation by 2, what do you have?

Answer 24

I mean 2*(x= 8 +4t) ,

Answer 25

x=16+8t ?

Answer 26

2x = 16 +8t , right? not just x

Answer 27

ohh yeah sorry

Answer 28

so, 8t =?

Answer 29

8t=2x-16 ?

Answer 30

yup, now the second equation is y =-1+8t
hence 8t=?

Answer 31

same thing, 2x-16?

Answer 32

nope, redo, just +1 both sides

Answer 33

what do you mean

Answer 34

y = -1+8t
+1 both sides
y +1 =8t or 8t =y+1
got it?

Answer 35

okayy

Answer 36

Now, combine the 2:
8t= 2x-16
8t = y +1
that is y+1= 2x-16 , right?

Answer 37

yup

Answer 38

then y =?

Answer 39

y=2x-17 ?

Answer 40

yup

Answer 41

now,everything is down on x, y, right? look at your first graph, look at a specific point.

Answer 42

its the third graph?

Answer 43

the x-intersection point is (8.5,0) right? that is if x =8.5, then y =0

Answer 44

alright

Answer 45

so, check. Oh, I am sorry, your guess is correct, just I was wrong.

Answer 46

you can also think of it in this sense...

when t = 0, x = 8+4(0) = 8
also, y = -1+8(0) = -1

so the line must go through the point (8, -1)

additionally, the change in x w.r.t. t = 4 (if you've had calculus, dx/dt = 4)

and the change in y w.r.t. t = 8 (if you've had calculus, dy/dt = 8)

so dy/dx = m = (dy/dt)/(dx/dt) = 8/4 = 2

now you have a point and a slope to get what you want

Answer 47

I got to go. good luck

Answer 48

So it is the third graph?? And thanks alot @loser66 !

Answer 49

@pgpilot326

Answer 50

why would it be the 3rd graph?

Answer 51

Because it goes through 8

Answer 52

yeah it goes through (8,0)... not (8, -1). where is the point when t = 0?

Answer 53

so which one is it?

Answer 54

what is x when t = 0? what is y when t = 0?

Answer 55

Idk how to find that

Answer 56

use the parametric equations!

Answer 57

x = 8 + 4t

y = -1 + 8t

Answer 58

What do i do with that