Question

Write an equation in slope-intercept form of the line that passes through (1,9) and (-3, – 9)

Answer 1

EXPLANATION

Given the ordered pairs: (1,9) and (-3,-9)

Slope-intercept form definition is:

y=mx+ b

is the slope-intercept form of a line where m is the slope and b is the y-intercept.

Compute the slope (1,9) and (-3,-9):

Slope between two points:

`\text{Slope = }((y2-y1))/((x2-x1))`

(x1,y1) = (1,9) (x2,y2) = (-3,-9)

`m=((-9-9))/((-3-1))=\text{ }(9)/(2)`

Compute the y-intercept:

Plug the slope 9/2 into y= mx +b

y=9/2x + b

Plug in (1,9):

9= 9/2*1 + b

Switch sides:

9/2 + b = 9

Subtract 9/2 from both sides:

9/2 + b -9/2 = 9 -9/2

Simplify:

b = 9/2

Construct the line equation y=mx+b where m=9/2 and b=9/2

y= 9/2x + 9/2

A