Algebra Help? Stuck on this last problem...?

Question

I'm getting confused with my math homework for this weekend :( I'm in Algebra 2. I've done the first 9 problems and am on the last 2 so don't think I'm lazy, I'm just stuck and need someone to tell me how to work this out.

Scenario:

You plant a small seedling. After 2 weeks, the plant is 154 millimeters tall. After 5 weeks, the plant is 226 millimeters tall. Assume that the plant grows at a constant rate.

What I have:

The two points given in the problem statement: (2,154) & (5,226)

The equation: y = 24x + 106

Now I'm supposed to figure out the height of the seedling when I first planted it and how long it will take for it to reach 1 meter if it grows at the same rate.

I just don't know what I'm supposed to to find out the height when it started. Cross multiplying with 0/X didn't work; I got different answers...

Please explain :)

Answer 1

so far you've done great.  You have the correct equation.  All you need to do is realize that the x value represents time given in weeks and y represents height given in millimeters.For the first question let x=0 since no time had passed when you first planted it.  Now solve for y (the height).For the second question, let y=1000 millimeters (same as 1 meter but in the correct units).  Now solve for x.Good luck.