Economics 3364A/B Lecture Notes - Lecture 5: Product Rule, Quotient Rule
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Do not simplify. (a) f (x) = x tan x, (b) f (x) = tan 1 x x2+1 , (c) f (x) = sec2( x2 + x),(d) f (x) = 3arccos x. Solution to 1-(a): by the product rule of di erentiaion, we have f (x) = ( x) tan x + x(tan x) = Solution to 1-(b): by the quotient rule of di erentiation, we have f (x) = (tan 1 x) (x2 + 1) (tan 1 x)(x2 + 1) (x2 + 1)2. 1 x2+1 (x2 + 1) (tan 1 x)(2x) (x2 + 1)2. 1 2x tan 1 x (x2 + 1)2. Solution to 1-(c): by the chain rule of di erentiation, we have f (x) = 2 sec(px2 + x) [sec(px2 + x)] . = 2 sec(px2 + x)[sec(px2 + x) tan(px2 + x)] (px2 + x) . = 2 sec2(px2 + x) tan(px2 + x) Solution to 1-(d): f (x) = 3arccos x.