Question

Which is an equation of the line that passes through (-1,-5) and (-3,-7)?

Answer 1

Remember that the slope intercept formula is:

y = mx + b

m is the slope

b is the y-intercept

Let's first find the slope. Below is how you find the slope using two points:

The formula for slope is

$\frac{y_{2}-y_{1}}{x_{2}-x_{1}}$

In this case we have the two points:

(-1, -5) and (-3, -7)

This means that:

$y_{2} =-7\\y_{1} =-5\\x_{2} =-3\\x_{1} =-1$

^^^Plug these numbers into the formula for slope...

$\frac{-7-(-5)}{-3-(-1)}$

$\frac{-2}{-2}$

1

^^^This is your slope

This is the formula we have so far:

y = 1x + b

OR

y = x + b

Now we must find b

To do that you must plug in one of the given points the line goes through in the x and y of the equation.

(-1, -5)

-5 = 1(-1) + b

-5 = -1 + b

-4 = b

(D) y = x - 4

Hope this helped!

~Just a girl in love with Shawn Mendes

Answer 2

Answer:

D

Step-by-step explanation:

The equation of a line in slope- intercept form is

y = mx + c ( m is the slope and c the y- intercept )

Calculate m using the slope formula

m = (y₂ - y₁ ) / (x₂ - x₁ )

with (x₁, y₁ ) = (- 1, - 5) and (x₂, y₂ ) = (- 3, - 7)

m = $\frac{-7+5}{-3+1}$ = $\frac{-2}{-2}$ = 1, hence

y = x + c ← is the partial equation of the line

To find c substitute either of the 2 points into the partial equation

Using (- 3, - 7), then

- 7 = - 3 + c ⇒ c = - 7 + 3 = - 4

y = x - 4 → D