Question

Need help with a problem involving slope-intercept equations.

Answer 1

Here it is: The graph of f is perpendicular to the line whose equation is 6 x - 7 y + 21 = 0 and has the same y-intercept as this line.

Answer 2

Hello?

Answer 3

ok. first you want to get it in slope-intercept form. y=mx+b so solve for y

Answer 4

Right. y = 6/7x+3.

Answer 5

And then the y-int. is y = 3.

Answer 6

Wait....

Answer 7

no.

Answer 8

Okay, but where do I go from there?

Answer 9

yes!

Answer 10

sorry yes. the y intercept is 3

Answer 11

Okay, wonderful.

Answer 12

ok.

Answer 13

if the slope is perpendicular to another, do you know what that means?

Answer 14

Yep.

Answer 15

It means that the slope of one is the negative reciprocal of the other.

Answer 16

right.

Answer 17

since you have the slope intercept form y=6/7x+3, what's the slope of this function?

Answer 18

-7/6x

Answer 19

- the x, sorry.

Answer 20

yeah, that would be the perpendicular slope. :)

Answer 21

and what's your y-intercept?

Answer 22

3. So...do I just plug -7/6 and (0,3) into y = mx + b?

Answer 23

yep

Answer 24

Well...then I'll get b = 3. So...presumably the answer is y = -7/6x + 3, right.

Answer 25

Okay, one sec.

Answer 26

yep

Answer 27

What if you know one point the graph passes through, as well as the x and y intercepts?

Answer 28

what do you mean?

Answer 29

Like okay. Here's another problem I have to do: The graph of f passes through (-8, 4) and is perpendicular to the line that has an x-intercept of 4 and a y-intercept of -36.

Answer 30

do you know the slope?

Answer 31

No.

Answer 32

oh! ok!

Answer 33

well, if you have the x and y intercepts, you have 2 points.

Answer 34

(4,0) and (0,-36)

Answer 35

Right, so I can just do this: (-36-0)/(0-4) to find the slope, right?

Answer 36

yes!

Answer 37

I.e., the slope's 4.

Answer 38

ok, now the perpendicular slope would be what?

Answer 39

-1/4

Answer 40

right, do you know the formula for the standard form?

Answer 41

like do you know how to find a function given a point and a slope?

Answer 42

Oh...wait...I can't just use point slope form? (i.e. y - y1 = m(x-x1))

Answer 43

haha yeah, you can

Answer 44

that's what I meant.

Answer 45

Oh, okay. Wonderful.

Answer 46

So...the answer's -1/4x+2?

Answer 47

Apparently not.

Answer 48

Really? That's what I would have gotten.

Answer 49

what's the answer?

Answer 50

No idea. The website we use in my class doesn't give us the answers.

Answer 51

let me check the algebra.

Answer 52

Awrighty.

Answer 53

slope is not 4. :P

Answer 54

-36/-4=6

Answer 55

not 4

Answer 56

Ahhh....I always make stupid mistakes like that!! Thank you..

Answer 57

So do I!

Answer 58

Yeah, sometimes being a human and not a calculator is frustrating xp

Answer 59

Anyway....I tried entering y - 4 = -1/6(x+8)...which is also apparently wrong.

Answer 60

I mean...I actually entered y = -1/6x + 8/3

Answer 61

did you try solving for y?

Answer 62

and that's wrong?

Answer 63

No, I'm supposed to enter the slope-intercept form.

Answer 64

And alas..yes, it is.

Answer 65

hmm?

Answer 66

it's wrong?

Answer 67

Yep.

Answer 68

hmm. I'm so confused.

Answer 69

Imagine how I feel lol

Answer 70

probably another algebra error on our parts. ok.

Answer 71

so the y intercept is -36 and the x is 4.

Answer 72

(0,-36) (4,0)

Answer 73

slope would be

Answer 74

-36-0/0-4=9!

Answer 75

I'm so sorry. I totally suck at algebra.

Answer 76

Oh....dammit!

Answer 77

My bad!

Answer 78

hate hate hate arithmetic. It's the bane of my existence

Answer 79

No, no, it's okay lol I should've noticed that.

Answer 80

I agree honestly. I always feel like I'm walking on eggshells.

Answer 81

same.

Answer 82

ok so now we have y-4=-1/9(x+8)

Answer 83

y-4=-1/9x+-8/9

Answer 84

y=-1/9x-8/9+4

Answer 85

Right, exactly. So...y= -1/9x + 28/9.

Answer 86

ok

Answer 87

Which is...RIGHT!!!

Answer 88

jeeze. so sorry about that.

Answer 89

No need to apologize. As I said, the fact that I didn't notice your error means I probably would've made one anyway xp

Answer 90

Regardless, thank you very much.

Answer 91

No worries. :)

Answer 92

Have a good day/night!

Answer 93

you too.