JAMB - Mathematics (2008 - No. 32)
Differentiate sin x - x cos x
x cos x
x sin x
-x cos x
-x sin x
คำอธิบาย
sin x - x cos x
dy/dx = cos x - [1.cos x + x -sin x]
= co x - [cos x - x sin x]
= cos x - cos x + x sin x
= x sin x
dy/dx = cos x - [1.cos x + x -sin x]
= co x - [cos x - x sin x]
= cos x - cos x + x sin x
= x sin x