Question

find an equation for the verticle line and the horizontal line through the given point

(1, 2/9)

Answer 1

please explain! (:

Answer 2

all vertical lines are of the form x = h, where h is any number

Answer 3

and all horizontal lines are of the form y = k, the k can be any number

Answer 4

so if you want a vertical line going through (1,2/9), then that vertical line must be x = 1

Answer 5

since all points on x = 1 have an x coordinate of 1

Answer 6

I'm sure you can see what the horizontal line must be

Answer 7

y= 2/9?
:)

Answer 8

you nailed it

Answer 9

thank you ! :)

Answer 10

you're welcome

Answer 11

mind just helping me on a few more? :3

Answer 12

sure I can help

Answer 13

how would you write an equation for a line that passes (3,2) and has a slope of -2/3

Answer 14

what is the general equation for slope intercept form

Answer 15

y= mx+b?

Answer 16

what is m? what is b?

Answer 17

m is the slope and b is the y?

Answer 18

b is the y _____

fill in the blank

Answer 19

intercept

Answer 20

so any line is uniquely determined by its slope and y-intercept

Answer 21

if you know those two things, you can find the equation of the line

Answer 22

we have the slope, which is -2/3, so that means m = -2/3

Answer 23

so y= -2/3x+ 2

Answer 24

but we don't know the y-intercept

Answer 25

oh..

Answer 26

that's if we had (0,2) as a point on the line

Answer 27

ok

Answer 28

we have (3,2) instead

Answer 29

so what we do is plug in x = 3 and y = 2 since that's what (3,2) means

Answer 30

y = mx + b

y = (-2/3)x + b ... plug in the given slope

2 = (-2/3)*(3) + b ... plug in the given point

Answer 31

notice how every variable but b has been replaced

you can now solve for b

Answer 32

I'll let you do that

Answer 33

so b=4?

Answer 34

good, so m = -2/3 (given) and b = 4 (just found out)

Answer 35

therefore, the equation is

\[\large y = -\frac{2}{3}x + 4\]

Answer 36

:) yay! ok

Answer 37

glad it's all clicking

Answer 38

so for the problem what's the equation if the line asses through (-4,9) and has no slope would b=9??

Answer 39

which type of lines have no slope?

Answer 40

.__.

Answer 41

horizontal :D

Answer 42

no horizontal lines have a slope of 0

Answer 43

or verticle? ._.

Answer 44

vertical lines have no slope or an undefined slope

Answer 45

ok, :) so it's just be y=-4?

Answer 46

y = -4 is a horizontal line

why?

because EVERY point on this line has a y coordinate of -4

Answer 47

so that's not the answer

Answer 48

i'm confusedd.. :(

Answer 49

think of two points that have a y coordinate of -4

Answer 50

(1,-4) (2,-4) ?

Answer 51

plot those two points and draw a straight line through them

Answer 52

lol........ >.<

Answer 53

wow.

Answer 54

what kind of line did you plot

Answer 55

horizontal :p

Answer 56

>.< silly me

Answer 57

its ok, it's all part of the learning process

Answer 58

so what you want is a vertical line through (-4, 9)

Answer 59

since all vertical lines have no slopes

Answer 60

x=-4....... ?? :3

Answer 61

good

Answer 62

you're a pro already

Answer 63

Lol NO :(

Answer 64

yes you are, just keep practicing and you'll get better

Answer 65

what happens when they don't tell you if it has a slope or not?

Answer 66

what do you mean

Answer 67

the question is Write the equation that has a y-intercept -3 and x-intercept -8?

Answer 68

is that kinda the same as the last one?

Answer 69

when they say y-intercept -3, what dos that mean?

Answer 70

does*

Answer 71

that (_,-3)...... .__. ? lol

Answer 72

what goes in that blank

Answer 73

b= -3?

Answer 74

yes that is true

Answer 75

but what do you know about a point on this line if the y-intercept is -3

Answer 76

a y-intercept of -3 means that the line crosses the y-axis at -3 on the y-axis