Use the ordered pairs to write a function rule. Give the rule in the slope-intercept form.

(–12, 1.5), (−1, –1.25), (5, –2.75), (8, −3.5)

Please explain how you got your slope and how you found b.

Respuesta :

Answer:

(−1, –1.25), (5, –2.75)

Step-by-step explanation:

If "slope-intercept form" is mentioned, then we already know that the function rule is that of a straight line with slope m and y-intercept b.

As we go from (−1, –1.25) to (5, –2.75), x increases by 6 and y decreases by 1.50.  Thus, the slope, m, is m = rise / run = -1.50 / 6, or m = -0.25 or -1/4.

Choosing one of the given points at random:  (8, -3.5), we start with the slope-intercept form y = mx + b and substitute -1/4 for m, 8 for x and -3.5 for y:    y = mx + b  becomes  -3.5 = (-1/4)(8) + b.  Then -3.5 + 2 = b, or b = -1.5.

The desired equation is y = (-1/4)x - 3/2, or y = -0.25x - 1.5