Question

find an equation for the line with the points 3,-7 and -6,9 in the general form Ax+By=C

Answer 1

help

Answer 2

Did you find the slope of the line?

Answer 3

no

Answer 4

That would be the first step. Do you know how to find the slope?

Answer 5

yeah

Answer 6

Ok. Do it and tell me what you get.

Answer 7

-16/9

Answer 8

That's what I got.

Answer 9

Now pick one of the points. Which one do you choose?

Answer 10

3,-7

Answer 11

\[y-y _{1}=m(x-x _{1})\]

Answer 12

Put -7 in place of y1. Put -16/9 in place of m and put 3 in place of x1

Answer 13

\[y-(-7)=-\frac{16}{9}(x-3)\]
\[y+7=\frac{-16}{9}x+\frac{16}{3}\]
\[y=\frac{-16}{9}x-\frac{5}{3}\]

Answer 14

Is that what you got?

Answer 15

no, if you minus 7, u have to minus it from both sides

Answer 16

that , and its not in the form Ax+By=C

Answer 17

Whoops. I forgot about that part. Let's rearrange it.

Answer 18

the actual answer is 16x+9y=-15, but i dont know how to get there

Answer 19

\[y=\frac{-16}{9}x-\frac{5}{3}\]
Multiply both sides by 9 to clear the fractions

Answer 20

\[9(y)=9(\frac{-16}{9})x-9(\frac{-5}{3})\]

Answer 21

\[9y=-16x+15\]

Answer 22

Correction: 9y=-16x-15

Answer 23

16x+9y=-15

Answer 24

how did you get 5-3?

Answer 25

i mean 5/3

Answer 26

16/3-7

Answer 27

\[y+7=\frac{-16}{9}x+\frac{16}{3}\]

Answer 28

subtract 7 from both sides in that equation.

Answer 29

16/3-7=-5/3

Answer 30

so u use point slope form to find b, then rearange to fit Ax+By=c?

Answer 31

yes. or you could use slope-intercept form if you prefer.

Answer 32

how would slope intercept work

Answer 33

\[y=mx+b\]
\[7=\frac{-16}{9}(3)+b\]

Answer 34

Make the 7 negative.

Answer 35

\[-7=\frac{-16}{3}+b\]

Answer 36

Add 16/3 to both sides.

Answer 37

\[\frac{-5}{3}=b\]

Answer 38

\[y=\frac{-16}{9}x-\frac{5}{3}\]

Answer 39

do you understand?

Answer 40

awsome, thank you

Answer 41

yw. Now practice some more problems so you can fix it in your mind.