Question

What is the equation of this line in standard form?

A - 9x−8y=23

B - 8x−9y=−23

C - 8x−9y=23

D
8x−7y=−25

Answer 1

The correct answer is B

Explanation:

I went a weird way to get this. I wrot the line in the slope intercept form and then converted it to the standare form.

For the slope intercept form I need a slope and a y interctp. I used the two points given to find the slope. The slope is the change in y over the change in x. From the points the y values are 3 and -1. The x values are 1.2 and -4

`(3 - -1)/((1)/(2)- - 4 )` =
`(3+1)/((1)/(4)+4 )` =
`(4)/((9)/(2) )`

4 ÷
`(9)/(2)` =
`(4)/(1)` x
`(2)/(9)` =
`(8)/(9)`

`(8)/(9)` is the slope

Now to find the y intercept

I will use

slope
`(8)/(9)` (m)

y = -1 from the point (-4,-1) given

x = -4 from the point (-4,-1) given

y=mx + b

-1 =
`(8)/(9)`(-4) + b

-1 =
`(-32)/(9)`x + b Add
`(32)/(9)` to both sides

`(23)/(9)` = b

y =
`(8)/(9)`x +
`(23)/(9)` Multiply all the way thorugh by 9

9y = 8x + 23 Subtract 9y from both sides

0 = 8x -9y + 23 Subtract 23 from both sides

-23 = 8x -9y

or

8x -9y = -23