Question

What is the equation of the line that contains the point (–5, –1) and has a slope of 4? Write in slope-intercept form.
A.
y = 4x – 19
B.
y = 4x + 19
C.
y = 4x – 1
D.
y = 4x + 1

Answer 1

First, we can plug it into point-slope form.

\(\sf y - y_1 = m(x - x_1)\)

Where y1 is the y-value of the point, x1 is the x-value of the point, and 'm' is the slope.

Answer 2

So we have:

(-5, -1)
Slope of 4

So:

(-5, -1)
x1 y1

m = 4

Answer 3

Can you plug those values into the equation I gave?

Answer 4

It isn't.

Answer 5

y=4x-1

Answer 6

or would it be y=4x+1

Answer 7

@butterflydreamer

Answer 8

let's check.
So we know for both your questions you have chosen, the slope (m) = 4 so that's correct.
Now check by substituting in your point (-5 , -1)
So for the first one you chose:
" y = 4x - 1"
Sub in x = -5 and y = -1 and we get:
-1 = 4 ( -5) - 1
simplify
-1 = -20 -1
-1 = -21
does -1 equal to -21? I don't think so .. so this is NOT correct :)

Next you chose " y = 4x + 1"
Sub in x = -5 and y = -1
-1 = 4 ( -5) + 1
-1 = 4 ( -5) + 1
-1 = -20 + 1
-1 = -19
This is also incorrect... SOOOOO we've eliminated two options

Answer 9

@moomoo222

We get this if we plug the numbers in correctly:

\(\sf y + 1 = 4(x + 5)\)

Can you distribute 4 then subtract 1 to both sides? That will give you your answer.

Answer 10

you could just sub your slope(m) and your points (x,y) into y = mx + b...and solve for b...and there is your equation

Answer 11

so it would be A?

Answer 12

or you can do what igreen says and use y - y1 = m(x - x1)

Answer 13

no it would be c not a

Answer 14

you can check if A is correct.
Sub in x = -5 , y = -1 and m = 4 into that option
So option A is :
y = 4x – 19
-1 = 4 ( -5) - 19
-1 = -20 - 19
-1 = -39
So not quite right..

Answer 15

so it is either c or d

Answer 16

for this question just use the point-slope formula first:
y- y1 = m ( x - x1)
m = 4 , x1 = -5 , y1 = -1
so we get,
y + 1 = 4 ( x +5 )

Then see the "x + 5" in the brackets? We want to multiply both the x and the 5 by 4
So
y +1 = 4x + 20
Then just subtract 1 from both sides. (by doing this, we get it into slope - int form : y = mx+b)

y + 1 - 1 = 4x + 20 - 1
y = 4x + 19

Answer 17

that is A

Answer 18

But a can't be the answer

Answer 19

it is B

Answer 20

correct. it's B