Question

need help; Find the equation of the line given a slope of 2/3 and a point (5, -4) ? so solve for y=mx+b in which I need b (y-intercept)

Answer 1

In this case, don't use the slope-intercept formula. Use the point slope form: \(y - y_1 = m(x - x_1)\)

Answer 2

to find b?

Answer 3

@bpaquin007 No. Don't use the slope-intercept form at all. Use the point-slope form, then if required rebuild the equation to slope-intercept form.

Answer 4

I see no reason why you can't use y = mx + b and solve for b. Then write your equation of the line.

Answer 5

whast the awnser then? I keep getting 14/3 = b

Answer 6

its supposed to be y=2/3x = 22/3

Answer 7

but I don't know how to get there

Answer 8

y = mx + b
-4 = 2/3(5) + b
-4 = 10/3 + b
-4 - 10/3 = b
-12/3 - 10/3 = b
-22/3 = b

your equation is : y = 2/3x - 22/3

Answer 9

are you still confused ?

Answer 10

kind of

Answer 11

can you explain it but maybe in words

Answer 12

y = mx + b
slope(m) = 2/3
(5,-4) x = 5 and y = -4
sub your stuff into the formula
y = mx + b
-4 = 2/3(5) + b

you understanding so far ?

Answer 13

yep

Answer 14

@texaschic101 Why should you solve for b when you can plug in directly with another form of the same equation, then rebuild your way back to the original form of equation you want?

Answer 15

y + 4 = 2/3(x - 5)
y = 2/3x - 10/3 + 4
y = 2/3x + 2/3

You can't get easier than that.

Answer 16

Uh:
y = 2/3x - 10/3 - 4
y = 2/3x - 22/3

Whatever is wrong with my brain...

Answer 17

-4 = 2/3(5) + b -- distribute through the parenthesis
-4 = 10/3 + b -- subtract 10/3 from both sides
-4 - 10/3 = 10/3 - 10/3 + b
as you can see, the 10/3's cancel out on the right side
now we have :
-4 - 10/3 = b
-4 is the same as -4/1...we are dealing with fractions, so we need a common denominator, which is 3. Thus turning -4/1 into -12/3.
Now we have :
-12/3 - 10/3 = b
add the two fractions and keep the negative sign
-22/3 = b

now put it into your equation.....remember m = 2/3
y = 2/3x - 22/3

does that help ?

Answer 18

you there texas?

Answer 19

yep...I am here....I tried to explain in great detail...do you understand ?

Answer 20

@texaschic101 You are overcomplicating the solution.

@bpaquin007 See my solution, which happens in 3 lines.

Answer 21

THank you so much texas!!! I got it:)

Answer 22

The reason my solution is taking so long is because I am including every step

Answer 23

you can solve this by using y = mx + b or y - y1 = m(x - x1)...whichever way is easier for you to do.

Answer 24

texas I have another question for you if your still here

Answer 25

lets see it :)

Answer 26

find the equation of the line given these two points: (-2,-1) and (9,-3)

Answer 27

do you know how to find the slope ?

Answer 28

yeah the slope is -2/11, you could skip that part

Answer 29

y - y1 = m(x - x1)
slope(m) = -2/11
(-2,-1) x1 = -2 and y1 = -1

now we sub
y - (-1) = -2/11(x - (-2)
y + 1 = -2/11(x + 2)
y + 1 = -2/11x - 4/11
y = -2/11x - 4/11 - 1
y = -2/11x - 4/11 - 11/11
y = -2/11x - 15/11

Answer 30

apparently the awnser is y=-2/11x + 7/11

Answer 31

thaats what my teacher wrote down

Answer 32

let me try again....
y - y1 = m(x - x1)
(9,-3) x1 = 9 and y1 = -3
now we sub
y - (-3) = -2/11(x - 9)
y + 3 = -2/11x + 18/11
y = -2/11x + 18/11 - 3
y = -2/11x + 18/11 - 33/11
y = -2/11x - 15/11

hmmm.. I am getting the same answer by using the other point as well.

Answer 33

I am sorry...I lost track of time...I have to go now. Get somebody else to check this if you want to make sure