Hmmmm,an algebra question

[SusanAR]

My dd, who is in ps adv. algebra I, brought home a worksheet with this problem:

You belong to a health and fitness center. You and your friends enrolled in the centers weight-loss program. The charts contain input and output values (assume that wek is input and weight is output) that represent the weight over a four week period for you and your two friends. Determine which of the charts contain data that is linear and explain why.
A. week 1 2 3 4
weight 150 147 144 141


B. week 1 2 3 4
weight 183 178 174 171


Now, I realize that chart A represents a 'function' (3 lbs. per week) and chart B does not; however, I say that chart B is still linear---- right??? What am I missing?

Susan

[CynthiaOK]

A plot of the points in chart B would yield a curved line. With every unit week, there is a smaller decrease in weight (5, 4, 3). Whereas in chart A, there is a consistent decrease with each week (3 lbs). So, chart A would be linear, chart B would be a curve.

[kiana]

Linear would imply that it's a straight line with constant slope.
The slope in the second one is not constant. If you graphed it, the points would not form a straight line.

Chart B can still represent a function, btw. A function is just a rule that associates an output to each input.