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Find 
lim_(x rarr1)(sqrt(5x+4)-3)/(x-1).
Choose 1 answer:
(A) 
(3)/(5)
(B) 
(5)/(6)
(C) 1
(D) The limit doesn't exist

Find limx15x+43x1 \lim _{x \rightarrow 1} \frac{\sqrt{5 x+4}-3}{x-1} .\newlineChoose 11 answer:\newline(A) 35 \frac{3}{5} \newline(B) 56 \frac{5}{6} \newline(C) 11\newline(D) The limit doesn't exist

Full solution

Q. Find limx15x+43x1 \lim _{x \rightarrow 1} \frac{\sqrt{5 x+4}-3}{x-1} .\newlineChoose 11 answer:\newline(A) 35 \frac{3}{5} \newline(B) 56 \frac{5}{6} \newline(C) 11\newline(D) The limit doesn't exist
  1. Identify the form: Identify the form of the limit.\newlineWe need to find the limit of the function (5x+43)/(x1)(\sqrt{5x+4}-3)/(x-1) as xx approaches 11. Let's first substitute xx with 11 to see if we can directly evaluate the limit.\newlinelimx1(5x+43)/(x1)=(51+43)/(11)=(93)/0=(33)/0=0/0\lim_{x \to 1}(\sqrt{5x+4}-3)/(x-1) = (\sqrt{5\cdot 1+4}-3)/(1-1) = (\sqrt{9}-3)/0 = (3-3)/0 = 0/0\newlineWe get an indeterminate form 0/00/0, which means we need to apply a different method to evaluate the limit.
  2. Apply algebraic manipulation: Apply algebraic manipulation to simplify the expression.\newlineTo resolve the indeterminate form, we can multiply the numerator and the denominator by the conjugate of the numerator. The conjugate of 5x+43\sqrt{5x+4}-3 is 5x+4+3\sqrt{5x+4}+3.\newlinelimx1(5x+43x1)(5x+4+35x+4+3)\lim_{x \to 1}\left(\frac{\sqrt{5x+4}-3}{x-1}\right)\left(\frac{\sqrt{5x+4}+3}{\sqrt{5x+4}+3}\right)
  3. Perform the multiplication: Perform the multiplication in the numerator.\newlineWhen we multiply the conjugate pairs in the numerator, we get a difference of squares, which simplifies to:\newline(5x+4)2(3)2=(5x+4)9=5x5(\sqrt{5x+4})^2 - (3)^2 = (5x+4) - 9 = 5x - 5\newlineThe denominator remains as (x1)(5x+4+3)(x-1)(\sqrt{5x+4}+3).\newlinelimx15x5(x1)(5x+4+3)\lim_{x \to 1}\frac{5x - 5}{(x-1)(\sqrt{5x+4}+3)}
  4. Simplify the expression further: Simplify the expression further.\newlineWe notice that the numerator 5x55x - 5 can be factored out as 5(x1)5(x - 1). This will allow us to cancel out the (x1)(x - 1) term in the denominator.\newlinelimx15(x1)(x1)(5x+4+3)\lim_{x \to 1}\frac{5(x - 1)}{(x-1)(\sqrt{5x+4}+3)}\newlineAfter canceling out the (x1)(x - 1) terms, we get:\newlinelimx15(5x+4+3)\lim_{x \to 1}\frac{5}{(\sqrt{5x+4}+3)}
  5. Evaluate the limit: Evaluate the limit of the simplified expression.\newlineNow that we have simplified the expression, we can directly substitute xx with 11 to find the limit.\newlinelimx15(51+4+3)=5(9+3)=5(3+3)=56\lim_{x \to 1}\frac{5}{(\sqrt{5*1+4}+3)} = \frac{5}{(\sqrt{9}+3)} = \frac{5}{(3+3)} = \frac{5}{6}

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