# Math Help - Help with simple differentiation

1. ## Help with simple differentiation

Hi,
How do I solve for the following: $d/dx [(0.1x + 0.4)log(0.1x + 0.4)]?$

I got the following answer but I think its wrong: $(1/ln2) + 0.1log(0.1x + 0.4).$

Can somebody help?

2. what base log are you using ?

at any rate I'll assume log base 2 from your answer
first of all use the product rule:

[.1x+.4] ' log(.1x+.4) + [.1x+.4] [log(.1x+.4)] '

= .1 log(.1x +.4) + {1/ln(2)}(.1x +.4)(.1/(.1x + .4)

= .1 log(.1x +.4) + .1/ln(2)

3. Yes, its base 2. Thanks.