Question

Sarah’s hair is 7 centimeters long. Her hair grows 1.5 centimeters per month. Sarah wants her hair to grow so that it is more than 25 centimeters long. Write an inequality to represent how many months she needs to grow her hair.

Answer 1

25 < 1.5x + 7

Explanation:

Let's call x the number of months that her hair needs to grow. It will grow at 1.5 cm per month. So for each month, it grows 1.5 cm. As an equation, that would be 1.5x.

It's currently 7 centimeters. (That is your intercept; it's your starting point.)

We want it to be MORE than 25. So we don't want it EQUAL to 25; we want our equation to be GREATER than 25.

25 < 1.5x + 7

Try it out - - - after 13 months, how long would her hair be?

25 < 1.5(13) + 7

25 < 19.5 + 7

25 < 26.5

After 3 months, her hair would be GREATER than 25 cm long because it would be 26.5 cm.

Answer 2

It needs to be at least 12 months