# I am stuck on PD Session 3 Phase 3 #7

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!!!

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 wasnâ€™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

Hey Lisa:

Thanks for this equation. I for got the ^2 in my equation, so I couldnâ€™t get it to solve correctly. I just donâ€™t see how to get the Examples written using the existing blocks. Could you email me one of your examples?

Thanks, Bob

Hereâ€™s a picture of one example I usedâ€¦

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

You are truly a rocket scientist and I canâ€™t tell you how long I was working on the applications to try to figure out the pattern.

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