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Find 
lim_(x rarr4)(x-4)/(3-sqrt(x+5))
Choose 1 answer:
(A) -6
(B) 
-(4)/(3)
(C) 
-(10)/(3)
(D) The limit doesn't exist

Find limx4x43x+5 \lim _{x \rightarrow 4} \frac{x-4}{3-\sqrt{x+5}} .\newlineChoose 11 answer:\newline(A) 6-6\newline(B) 43 -\frac{4}{3} \newline(C) 103 -\frac{10}{3} \newlineD The limit doesn't exist

Full solution

Q. Find limx4x43x+5 \lim _{x \rightarrow 4} \frac{x-4}{3-\sqrt{x+5}} .\newlineChoose 11 answer:\newline(A) 6-6\newline(B) 43 -\frac{4}{3} \newline(C) 103 -\frac{10}{3} \newlineD The limit doesn't exist
  1. Identify Limit Form: Identify the form of the limit as xx approaches 44. We need to check if the limit results in an indeterminate form by substituting x=4x = 4 into the expression (x4)/(3x+5)(x-4)/(3-\sqrt{x+5}). Calculate the numerator and denominator separately: Numerator: x4=44=0x - 4 = 4 - 4 = 0 Denominator: 3x+5=34+5=39=33=03 - \sqrt{x + 5} = 3 - \sqrt{4 + 5} = 3 - \sqrt{9} = 3 - 3 = 0 Since both the numerator and denominator are 00, we have an indeterminate form of 0/00/0.
  2. Check Indeterminate Form: Simplify the expression to resolve the indeterminate form.\newlineWe can use algebraic manipulation to simplify the expression. One common technique is to multiply the numerator and the denominator by the conjugate of the denominator.\newlineThe conjugate of the denominator 3x+53 - \sqrt{x + 5} is 3+x+53 + \sqrt{x + 5}.\newlineMultiply the original expression by (3+x+5)/(3+x+5)(3 + \sqrt{x + 5})/(3 + \sqrt{x + 5}):\newlinelimx4(x4)(3+x+5)(3x+5)(3+x+5)\lim_{x \rightarrow 4} \frac{(x-4)(3 + \sqrt{x + 5})}{(3 - \sqrt{x + 5})(3 + \sqrt{x + 5})}
  3. Simplify Expression: Perform the multiplication in the numerator and use the difference of squares in the denominator.\newlineNumerator: (x4)(3+x+5)(x - 4)(3 + \sqrt{x + 5})\newlineDenominator: (3x+5)(3+x+5)=32(x+5)2(3 - \sqrt{x + 5})(3 + \sqrt{x + 5}) = 3^2 - (\sqrt{x + 5})^2\newlineNow, simplify the denominator:\newlineDenominator: 9(x+5)=9x5=4x9 - (x + 5) = 9 - x - 5 = 4 - x
  4. Perform Multiplication: Notice that the numerator can be simplified further.\newlineWe can expand the numerator:\newlineNumerator: x×3+x×x+54×34×x+5x \times 3 + x \times \sqrt{x + 5} - 4 \times 3 - 4 \times \sqrt{x + 5}\newlineSimplify the numerator:\newlineNumerator: 3x+x×x+5124×x+53x + x \times \sqrt{x + 5} - 12 - 4 \times \sqrt{x + 5}
  5. Simplify Numerator: Cancel out the common terms in the numerator and denominator.\newlineWe have a common term of x4x - 4 in the numerator and 4x4 - x in the denominator, which can be simplified to 1-1 when we reverse the order of the terms in the denominator.\newlineSo, the expression simplifies to:\newlinelimx41(3+x+5)1\lim_{x \to 4} \frac{-1(3 + \sqrt{x + 5})}{-1}\newlineThe 1-1 in the numerator and denominator cancel out, leaving us with:\newlinelimx4(3+x+5)\lim_{x \to 4} (3 + \sqrt{x + 5})
  6. Cancel Common Terms: Evaluate the limit by substituting x=4x = 4 into the simplified expression.\newlinelimx4(3+x+5)=3+4+5=3+9=3+3=6\lim_{x \to 4} (3 + \sqrt{x + 5}) = 3 + \sqrt{4 + 5} = 3 + \sqrt{9} = 3 + 3 = 6\newlineHowever, we must remember that we canceled a negative sign in Step 55, so the actual limit is the negative of this result:\newlineFinal limit: 6-6

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