M Mehgan New member Joined Feb 6, 2006 Messages 11 Feb 13, 2006 #1 Here's the problem: Find the derivative for f(x)= (x^-2+x^-3)(x^5-2x^2) The answer I got was: f'(x)= (5x^5+5x^4-4x^2-4x/x^3)+(-3x^9+2x^8+6x^6-4x^5/6x^7) Can anyone tell me if this is right? Thanks very much!
Here's the problem: Find the derivative for f(x)= (x^-2+x^-3)(x^5-2x^2) The answer I got was: f'(x)= (5x^5+5x^4-4x^2-4x/x^3)+(-3x^9+2x^8+6x^6-4x^5/6x^7) Can anyone tell me if this is right? Thanks very much!
W Weatherkid11 New member Joined Nov 15, 2005 Messages 6 Feb 13, 2006 #2 You use the product rule so (x^-2+x^-3)(5x^4-4x)+(x^5-2x^2)(-2x^-3-3x^-4) Then you simplify all that down
You use the product rule so (x^-2+x^-3)(5x^4-4x)+(x^5-2x^2)(-2x^-3-3x^-4) Then you simplify all that down
G galactus Super Moderator Staff member Joined Sep 28, 2005 Messages 7,203 Feb 13, 2006 #3 Is your problem: \(\displaystyle (x^{-2}+x^{-3})(x^{5}-2x^{2})\)? If so, you seem to have made it much more complicated than need be. You don't need the product rule. Just do the FOIL thing. You get \(\displaystyle x^{3}-2+x^{2}-2x^{-1}\) Now differentiate term by term. Easy as pi.
Is your problem: \(\displaystyle (x^{-2}+x^{-3})(x^{5}-2x^{2})\)? If so, you seem to have made it much more complicated than need be. You don't need the product rule. Just do the FOIL thing. You get \(\displaystyle x^{3}-2+x^{2}-2x^{-1}\) Now differentiate term by term. Easy as pi.
