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lim_(x rarr4)(-5x^(2)+20 x)/(x^(3)-3x^(2)-4x)=

limx45x2+20xx33x24x= \lim _{x \rightarrow 4} \frac{-5 x^{2}+20 x}{x^{3}-3 x^{2}-4 x}=

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Q. limx45x2+20xx33x24x= \lim _{x \rightarrow 4} \frac{-5 x^{2}+20 x}{x^{3}-3 x^{2}-4 x}=
  1. Identify Function: Identify the function to which we need to find the limit.\newlineWe are given the function (5x2+20x)/(x33x24x)(-5x^2 + 20x) / (x^3 - 3x^2 - 4x) and we need to find its limit as xx approaches 44.
  2. Substitute Value: Substitute the value of xx into the function to see if it results in an indeterminate form.\newlineLet's substitute x=4x = 4 into the function:\newline(-5(4)^2 + 20(4)) / ((4)^3 - 3(4)^2 - 4(4))\(\newline= (-5(16) + 80) / (64 - 3(16) - 16)\newline= (-80 + 80) / (64 - 48 - 16)\newline= 0 / 0\newlineWe get an indeterminate form \$0/0\), which means we need to simplify the function further to find the limit.
  3. Factor Numerator and Denominator: Factor the numerator and the denominator of the function.\(\newline\)We need to factor both the numerator and the denominator to see if there are common factors that can be canceled out.\(\newline\)Numerator: \(-5x^2 + 20x\) can be factored as \(-5x(x - 4)\)\(\newline\)Denominator: \(x^3 - 3x^2 - 4x\) can be factored as \(x(x^2 - 3x - 4)\)\(\newline\)Further factor the quadratic \(x^2 - 3x - 4\) as \((x - 4)(x + 1)\)\(\newline\)So the denominator becomes \(x(x - 4)(x + 1)\)
  4. Cancel Common Factors: Cancel out the common factors in the numerator and the denominator.\(\newline\)We have a common factor of \((x - 4)\) in both the numerator and the denominator.\(\newline\)After canceling out the common factor, the function simplifies to:\(\newline\)\(-5x / (x(x + 1))\)\(\newline\)\(= -5 / (x + 1)\)
  5. Substitute Simplified Function: Substitute the value of \(x\) into the simplified function to find the limit.\(\newline\)Now that we have simplified the function, let's substitute \(x = 4\) into the function:\(\newline\)\(-\frac{5}{(4 + 1)}\)\(\newline\)\(= -\frac{5}{5}\)\(\newline\)\(= -1\)

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