Differentiate the following from first principles

We need to find derivative of f(x) = √tan x


Derivative of a function f(x) is given by –


f’(x) = {where h is a very small positive number}


derivative of f(x) = √tan x is given as –


f’(x) =


f’(x) =


As the limit takes 0/0 form on putting h = 0. So we need to remove the indeterminate form. As the numerator expression has square root terms so we need to multiply numerator and denominator by √tan (x + h) + √tan x.


f’(x) =


Using (a + b)(a – b) = a2 – b2 ,we have –


f’(x) =


Using algebra of limits, we have –


f’(x) =


f’(x) =


f’(x) =


f’(x) =


Using: sin A cos B – cos A sin B = sin (A – B)


f’(x) =


Using algebra of limits we have –


f’(x) =


Use the formula –


f’(x) = ×


f’(x) =


Hence,


Derivative of f(x) = √tan(x) is


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