- #1

RawlinsCross

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## Homework Statement

I have a probability distribution function (PDF) going fromi 0 to a on the y-axis and 0 to 30 on the x-axis. The function describing the PDF is the quadratic equation f(x) = a+bx+cx^2

I have to find a, b, and c.

## Homework Equations

## The Attempt at a Solution

I know that three unknown require 3 equations.

1. By definition the area under a PDF = 1 so one equation is intergrating f(x) from 0 to 30 and have that equal to 1. When that's worked out you get 30a+450b+9000C=1

2. I know that when x = 30 f(x) = 0. Therefore we get a+30b+900 = 0

but what is the third equation? I know that when x = 0 f(x) = a but that's only the y-intercept

Any ideas?