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Given 
f(x)=(3)/(x+2), find 
f^(')(1) using the definition of a derivative.

Given f(x)=3x+2 f(x)=\frac{3}{x+2} , find f(1) f^{\prime}(1) using the definition of a derivative.

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Q. Given f(x)=3x+2 f(x)=\frac{3}{x+2} , find f(1) f^{\prime}(1) using the definition of a derivative.
  1. Given Function: We are given the function f(x)=3(x+2)f(x) = \frac{3}{(x+2)} and we need to find its derivative at x=1x = 1 using the definition of a derivative. The definition of a derivative is:\newlinef(x)=limh0f(x+h)f(x)hf'(x) = \lim_{h \to 0} \frac{f(x+h) - f(x)}{h}\newlineLet's apply this definition to our function.
  2. Substitute x+hx+h: First, we need to find the expression for f(x+h)f(x+h). This means we will substitute (x+h)(x+h) for xx in the function f(x)f(x):f(x+h)=3((x+h)+2)=3x+h+2f(x+h) = \frac{3}{((x+h)+2)} = \frac{3}{x+h+2}
  3. Plug into Derivative Definition: Now, we will plug f(x+h)f(x+h) and f(x)f(x) into the definition of the derivative: f(x)=limh0[3(x+h+2)3(x+2)]/hf'(x) = \lim_{h \to 0} \left[\frac{3}{(x+h+2)} - \frac{3}{(x+2)}\right] / h
  4. Find Common Denominator: Next, we need to find a common denominator for the terms in the numerator to combine them:\newlineThe common denominator is (x+h+2)(x+2)(x+h+2)(x+2), so we rewrite the numerator:\newlinef(x)=limh0[3(x+2)3(x+h+2)(x+h+2)(x+2)]/hf'(x) = \lim_{h \to 0} \left[\frac{3(x+2) - 3(x+h+2)}{(x+h+2)(x+2)}\right] / h
  5. Simplify Numerator: Now, we simplify the numerator:\newline3(x+2)3(x+h+2)=3x+63x3h6=3h3(x+2) - 3(x+h+2) = 3x + 6 - 3x - 3h - 6 = -3h\newlineSo the expression becomes:\newlinef(x)=limh0[3h((x+h+2)(x+2)h)]f'(x) = \lim_{h \to 0} \left[\frac{-3h}{((x+h+2)(x+2) \cdot h)}\right]
  6. Cancel out h: We can now cancel out the h in the numerator and denominator: f(x)=limh0[3((x+h+2)(x+2))]f'(x) = \lim_{h \to 0} \left[-\frac{3}{((x+h+2)(x+2))}\right]
  7. Take the Limit: Now we can take the limit as hh approaches 00:f(x)=3((x+2)(x+2))f'(x) = \frac{-3}{((x+2)(x+2))}
  8. Substitute x=1x=1: Finally, we substitute x=1x = 1 into the derivative to find f(1)f'(1):f(1)=3((1+2)(1+2))=3(3×3)=39=13f'(1) = -\frac{3}{((1+2)(1+2))} = -\frac{3}{(3\times3)} = -\frac{3}{9} = -\frac{1}{3}

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