I am stuck on PD Session 3 Phase 3 #7


#1

Hey Super Math GURUs!!!

The rocket-man as it does not make sense to go from 1sec to 15 feet and 2 seconds at 45 feet etc. Help!!!


#2

So this was actually Stage 4, Lesson #7.

Maybe I made this more complicated than it needed to be, but there was quite a bit of complicated math going on here!

I wasn’t sure if this was looking for a quadratic equation or an exponential equation, since the instructions mentioned both. I started with the quadratic formula, and it seems to have worked.

f(x) = ax^2 + bx + c

A. f(1) = a(1^2) + b(1) + c = 15
B. f(2) = a(2^2) + b(2) + c = 45
C. f(3) = a(3^2) + b(3) + c = 95
D. f(4) = a(4^2) + b(4) + c = 165

I solved the system of equations using:
B - 2A and C - 3A to get a two-variable system.

When all was said and done, I ended up with
a = 10, b = 0, and c = 5
So the equation is y = 10x^2 + 5


#3

Hey Lisa:

Thanks for this equation. I for got the ^2 in my equation, so I couldn’t get it to solve correctly. I just don’t see how to get the Examples written using the existing blocks. Could you email me one of your examples?

Thanks, Bob


#4

Here’s a picture of one example I used…


#5

Thanks so much for sharing! I was totally stuck on this. The way you guys solved it is way beyond my students’ capabilities at this point. Would there be another way to teach them how to approach this?


#6

You are truly a rocket scientist and I can’t tell you how long I was working on the applications to try to figure out the pattern.