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Find 
lim_(x rarr3)(x-3)/(sqrt(4x+4)-4).
Choose 1 answer:
(A) -4
(B) 1
(C) 2
(D) The limit doesn't exist

Find limx3x34x+44 \lim _{x \rightarrow 3} \frac{x-3}{\sqrt{4 x+4}-4} .\newlineChoose 11 answer:\newline(A) 4-4\newline(B) 11\newline(C) 22\newline(D) The limit doesn't exist

Full solution

Q. Find limx3x34x+44 \lim _{x \rightarrow 3} \frac{x-3}{\sqrt{4 x+4}-4} .\newlineChoose 11 answer:\newline(A) 4-4\newline(B) 11\newline(C) 22\newline(D) The limit doesn't exist
  1. Identify Indeterminate Form: Identify the indeterminate form.\newlineWe need to evaluate the limit of the function (x3)/(4x+44)(x-3)/(\sqrt{4x+4}-4) as xx approaches 33. Let's first plug in the value of x=3x = 3 to see if the function is defined at that point or if it results in an indeterminate form.\newlinelimx3x34x+44=3343+44=00\lim_{x \to 3}\frac{x-3}{\sqrt{4x+4}-4} = \frac{3-3}{\sqrt{4\cdot 3+4}-4} = \frac{0}{0}\newlineThis is an indeterminate form, so we cannot directly evaluate the limit.
  2. Rationalize Denominator: Rationalize the denominator.\newlineTo resolve the indeterminate form, we can multiply the numerator and the denominator by the conjugate of the denominator. The conjugate of 4x+44\sqrt{4x+4}-4 is 4x+4+4\sqrt{4x+4}+4.\newlinelimx3(x3)(4x+4+4)(4x+44)(4x+4+4)\lim_{x \to 3}\frac{(x-3)(\sqrt{4x+4}+4)}{(\sqrt{4x+4}-4)(\sqrt{4x+4}+4)}
  3. Apply Difference of Squares: Apply the difference of squares formula.\newlineWhen we multiply the denominator by its conjugate, we get a difference of squares, which simplifies to:\newline(4x+44)(4x+4+4)=(4x+4)2(4)2=4x+416=4x12(\sqrt{4x+4}-4)(\sqrt{4x+4}+4) = (\sqrt{4x+4})^2 - (4)^2 = 4x+4 - 16 = 4x - 12
  4. Simplify Expression: Simplify the expression.\newlineNow we simplify the numerator and the denominator separately:\newlineNumerator: (x3)(4x+4+4)(x-3)(\sqrt{4x+4}+4)\newlineDenominator: 4x124x - 12\newlineThe limit becomes:\newlinelimx3(x3)(4x+4+4)4x12\lim_{x \to 3}\frac{(x-3)(\sqrt{4x+4}+4)}{4x - 12}
  5. Factor Out Common Term: Factor out the common term in the denominator.\newlineWe notice that the denominator 4x124x - 12 can be factored out as 4(x3)4(x - 3). This will allow us to cancel out the (x3)(x-3) term in the numerator and the denominator.\newlinelimx3(x3)(4x+4+4)4(x3)\lim_{x \to 3}\frac{(x-3)(\sqrt{4x+4}+4)}{4(x - 3)}
  6. Cancel Common Terms: Cancel out the common terms.\newlineAfter factoring, we can cancel the (x3)(x-3) term in the numerator and the denominator:\newlinelimx3(4x+4+4)/4\lim_{x \to 3}\left(\sqrt{4x+4}+4\right)/4
  7. Plug in Value: Plug in the value of x=3x = 3. Now that we have simplified the expression and eliminated the indeterminate form, we can safely substitute x=3x = 3 into the limit: limx3(43+4+4)/4=(12+4+4)/4=(16+4)/4=(4+4)/4=8/4=2\lim_{x \to 3}(\sqrt{4\cdot 3+4}+4)/4 = (\sqrt{12+4}+4)/4 = (\sqrt{16}+4)/4 = (4+4)/4 = 8/4 = 2

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