Question

line n passes through the points (-3 -7.5) and (2 -5) tahlia determined that the equation of line n is y = 0.5x. explain the error Tahlia made while determining her equation. Be sure to include the correct equation in your explanation

Answer 1

She forgot the y-intercept

y = 0.5x - 6

Explanation:

y = 0.5x + c

-5 = 0.5(2) + c

c = -6

Correct equation:

y = 0.5x - 6

Answer 2

She forgot to find the y intercept add it in the equation

y = .5x-6

Explanation:

First we need to find the slope

m = (y2-y1)/(x2-x1)

= (-5 - -7.5)/ (2 - -3)

=(-5 +7.5)/( 2+3)

= 2.5/5

= 1/2

Substitute into the slope intercept form of the equation

y= mx+b

y= .5x +b

We need to determine b by substituting a point into the equation

-5 = .5(2) +b

-5 = 1+b

Subtract 1 from each side

-5-1 = 1-1+b

-6 = b

y = .5x-6