Question

Which of the following equations describes the line shown below? Check allthat apply.(-5,6)(-1,-1)

Answer 1

Options E and F are the correct options

Here, we need to get the equation of the line that passes through the two points given

Mathematically, the equation of a line can be generally expressed as ;

y = mx + c

where m is the slope of the line and c is the y-intercept of the lien ( where it crosses the y-axis)

To get the slope m , we are goint to use the formula below;

`\begin{gathered} m=\frac{y_2-y_1}{x_{2\text{ - }}x_1} \\ \\ x_{1\text{ }}=-5,x_2=-1,y_1\text{ = }6,y_2\text{ = -1} \end{gathered}`

Substituting these values into the slope equation , we have

m = (-1-(6))/(-1-(-5)) = -7/4

The equation is now in the form;

y = -7x/4 + c

what is left is to get the y-intercept

We can get the value of the y-intercept by substituting for x and y using any of the points

Let us use the second point

Here, x = -1 and y = -1

Thus;

-1 = -7(-1)/4 + c

-1 = 7/4 + c

c = -1-7/4 = -11/4

So the complete equation of the line is;

y = -7x/4 - 11/4

To properly answer the questions, we need the forms in the options that looks like or can be manipulated arithmetically to look like what we have as our answer

We proceed with each of the options one after the other to see if they can be written in the form of our answer

Option A

y - 5 = -7/4 ( x + 6)

Opening the bracket and evaluating;

y - 5 = -7x/4 - 42/4

y = -7x/4 -42/4 + 5

y = -7x/4 -22/4

we can see this is not a correct option

Option B

y - 6 = -4/7 (x + 5)

Multiply through by 7

7y - 42 = -4x - 20

7y = -4x - 20 + 42

7y = -4x + 22

divide through by 7

y = -4x/7 + 22/7

We can see this is incorrect also

Option C

y - 1 = -4/7(x-1)

Multiply through by 7

7y - 7 = -4x + 4

7y = -4x + 4 + 7

7y = -4x + 11

divide through by 7

y = -4x/7 + 11/7

This is incorrect too

Option D

y + 1 = -4/7 ( x + 1)

Multiply through by 7

7y + 7 = -4x - 4

7y = -4x -4 -7

7y = -4x - 11

y = -4x/7 - 11/7

This is incorrect also

Option E

y - 6 = -7/4 (x + 5)

Multiply through by 4

4y - 24 = -7x - 35

4y = -7x - 35 + 24

4y = -7x -11

y = -7x/4 - 11/4

This is a correct option

Option F

y + 1 = -7/4 ( x + 1)

Multiply through by 4

4y + 4 = -7x - 7

4y = -7x - 7-4

4y = -7x - 11

y = -7x/4 - 11/4

This is a correct option too