Monday

December 22, 2014

December 22, 2014

Posted by **superdiver** on Tuesday, October 2, 2012 at 6:01am.

If f(x)= (2x^2 - 5x - 3) / (3-x)

find f'(-8).

- calculus -
**Steve**, Tuesday, October 2, 2012 at 10:28amseparate the terms:

f(x) = 2x^2/(3-x) - 5x/(3-x) - 3/(3-x)

now use the quotient rule 3 times:

f'(x) = -2x(x-6)/(3-x)^2 - 15/(3-x)^2 - 3/(3-x)^2

However, this is a waste of time, since

(2x^2 - 5x - 3) = (x-3)(2x+1)

so, f(x) = -(2x+1)

f'(x) = -2 as long as x≠3

so, f'(-8) = -2

moral: see whether a function can be simplified before delving into long calculations.

**Answer this Question**

**Related Questions**

calculus - How do I solve this using the TERM BY TERM method? If f(x)= (2x^2 - ...

math - the 3rd term of a geometric progression is nine times the 1st term.if the...

math - The third term of a geometric progressiom is nine times the first term.if...

Maths - The 3rd term of an AP is 10 more than the first term while the fifth ...

math - The 3rd term of a geometric progression is nine times the first term.if ...

geometric progression - the 3rd term of a gpis 10 and the 6th term is 80 find ...

pre-calculus - Find the designated term of the binomial expansion. 5th term of (...

Math - 3,5,-5... The first term in the sequence of #'s shown above is 3. Each ...

Math - 1. Find the 12th term of the arithmetic sequence 2, 6, 10, … . 2. Solve ...

math - The 4th term of an AP is 3 times its first term and the 7 term exceeds ...