Question

Beverly is starting a new diet. Her current weight is 160 pounds. She expects to lose 4 pounds per month. If x represents the number of months Beverly is on the diet, which linear function models the situation?

A) y = 4x − 160
B) y = − 4x + 160
C) y =
1
4
x + 160
D) y = − 4x

Answer 1

In this context, you would be making a equation using the format: y=mx+b

M being your rate of change

X being the month

B being the starting number

Beverly is LOSING 4 pounds a month, so she would be decreasing by 4, or in other words, -4. That would be your M value

Beverly starts at 160, so that would be your B value

Your equation would look like this:

y= -4x+160

Your answer would be B. y = -4x +160

A) is not the answer because you can't be -160 pounds

C) is not the answer because the 1 is not part of the text.

D) is not the answer because 160 has to be used in the equation in order for it to make sense, you don't start at 0 pounds.

Answer 2

The answer is B) or y = -4x + 160

If her initial weight is 160 pounds, then you must subtract 4x, representing how much weight she lost over time, to find her current weight y

But, since y = 160 – 4x isn't an option, we can reverse to negatives as long as you change the addition/subtraction sign

So, subtracting positive 4x is the same as adding -4x

Therefore, y = 160 – 4x is the same as y = -4x + 160