Math  /  Calculus

Question4. Evaluale mathematically limx0xx+42\lim _{x \rightarrow 0} \frac{x}{\sqrt{x+4-2}}

Studdy Solution

STEP 1

1. We are tasked with evaluating the limit limx0xx+42\lim_{x \rightarrow 0} \frac{x}{\sqrt{x+4} - 2}.
2. The limit is evaluated as xx approaches 0.
3. The expression involves a square root, which suggests the possibility of rationalizing the denominator.

STEP 2

1. Identify the indeterminate form.
2. Rationalize the denominator.
3. Simplify the expression.
4. Evaluate the limit as xx approaches 0.

STEP 3

First, substitute x=0x = 0 into the expression to check for indeterminate forms:
00+42=022=00 \frac{0}{\sqrt{0+4} - 2} = \frac{0}{2 - 2} = \frac{0}{0}
This is an indeterminate form.

STEP 4

To resolve the indeterminate form, rationalize the denominator by multiplying the numerator and the denominator by the conjugate of the denominator:
xx+42×x+4+2x+4+2 \frac{x}{\sqrt{x+4} - 2} \times \frac{\sqrt{x+4} + 2}{\sqrt{x+4} + 2}

STEP 5

Multiply out the denominator using the difference of squares formula:
(x+42)(x+4+2)=(x+4)222=x+44=x (\sqrt{x+4} - 2)(\sqrt{x+4} + 2) = (\sqrt{x+4})^2 - 2^2 = x + 4 - 4 = x
The expression becomes:
x(x+4+2)x \frac{x(\sqrt{x+4} + 2)}{x}

STEP 6

Simplify the expression by canceling xx in the numerator and the denominator:
x+4+2 \sqrt{x+4} + 2

STEP 7

Evaluate the limit as xx approaches 0:
limx0(x+4+2)=0+4+2=4+2=2+2=4 \lim_{x \rightarrow 0} (\sqrt{x+4} + 2) = \sqrt{0+4} + 2 = \sqrt{4} + 2 = 2 + 2 = 4
The value of the limit is:
4 \boxed{4}

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