# 2 Differentiation Rule Questions HELP

1. Nov 2, 2004

### tink

Ok here are the questions....
1)Find the Parabola with equation y=ax^2 +bx +c that has slope 4 at x=1, slope -8 at x=-1 and passes through the point (2,15)

2)A manufacturer produces bolts of a fabric with a fixed width. The quantity q of this fabris that is sold is a function of the selling price p, so we can write q=f(p). Then the total revenue earned with selling prince p is R(p)=pf(p).
a) What does it mean to say that f(20)= 10 000 and f(20)= -350 (f prime) ???
b) Assuming the values in part (a), find R(20) and interpret your answer.

I need help!

thanks

2. Nov 2, 2004

### Pyrrhus

For the first problem

Use what you are given if the parabole goes throught the point (2,15)
then when its x=2. its y = 15. You know the slope is the first derivative right?, make your system of equations.

For the second problem,

Understand what the first derivative means.

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