1 answer
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f'= f(x+h)-f(x) / h as h >>0
= sqrt(2x+2h-1) - sqrt(2x-1) /h
multiply numerator by the conjugate...
= (2x+2h-1)-(2x-1) )/h(sqrt(2x+2h-1)+sqrt(2x-1) )
= 2h/(h(sqrt(2x+2h-1)+sqrt(2x-1) )
= 2/(2sqrt(2x-1)= 1/sqrt(2x-1)
check my thinking.