Please don't answer this unless you're sure because I keep getting wrong answers from some people!
Compute f ' (4) if f(x)=(-x^2)/(3) -5x
I put parenthese to show which parts are part of the division...note that the -5x is not in the division part
2007-02-15 14:39:34 · 4 answers · asked by Nicky 2 in Education & Reference ➔ Homework Help
You how to take a derivative right. Subtract the exponent by one and mutiply by that number.
For the first term subract one from 2 and multiply by 2. The second term simply becomes 5.
f'(x) = -2x/3 - 5
f'(4) = -2 * 4/3 - 5
f'(4) = - 8/3 - 5
Does this make sense?? Any questions??
2007-02-15 14:46:52 · answer #1 · answered by nicewknd 5 · 0⤊ 0⤋
Remember that multiplicative constants (like the 1/3 in your first term and the 5 in your second) can be pulled out of derivatives. So:
f'(x) = (-2x/3) - 5
Therefore,
f'(4) = (-2(4)/3) - 5 = -8/3 - 5 = -23/3
2007-02-15 22:44:25 · answer #2 · answered by Anonymous · 0⤊ 0⤋
First find the derivative of the function:
f(x) = -5x + -x^2/3
f'(x) = -5 + -2x/3
Now find the value you want:
f'(4) = -5 + -2(4)/3 = -5 + -8/3 = -15/3 - 8/3 = -23/3
2007-02-15 22:44:05 · answer #3 · answered by sinfonian0294 2 · 0⤊ 0⤋
f(x)=(-x^2)/(3) -5x
f'(x)=(-2x/3)-5
f'(4)=-2(4)/3-5
=-8/3 -5
=-23/5
2007-02-15 22:46:00 · answer #4 · answered by Glenn T 3 · 0⤊ 0⤋