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Solve the Following Question.(2 Marks)

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22 questions · timed · auto-graded

Question 12 Marks
Evaluate the following Limits:

Evaluate the limit of the function if exist at $x=1$ where,
$
f(x)= \begin{cases}7-4 x & x<1 \\ x^2+2 & x \geq 1\end{cases}
$

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Question 42 Marks
Evaluate the following Limits:

$\lim _{x \rightarrow 0}\left[\frac{\left(5^x-1\right)^2}{x \cdot \log (1+x)}\right]$

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Question 72 Marks
Evaluate the following Limits:

$\lim _{x \rightarrow 0}\left[\frac{a^x+b^x+c^x-3}{x}\right]$

Answer
$\begin{aligned} & \lim _{x \rightarrow 0} \frac{\mathrm{a}^x+\mathrm{b}^x+\mathrm{c}^x-3}{x} \\ & =\lim _{x \rightarrow 0} \frac{\left(\mathrm{a}^x-1\right)+\left(\mathrm{b}^x-1\right)+\left(\mathrm{c}^x-1\right)}{x} \\ & =\lim _{x \rightarrow 0}\left(\frac{\mathrm{a}^x-1}{x}+\frac{\mathrm{b}^x-1}{x}+\frac{\mathrm{c}^x-1}{x}\right) \\ & =\lim _{x \rightarrow 0}\left(\frac{\mathrm{a}^x-1}{x}\right)+\lim _{x \rightarrow 0}\left(\frac{\mathrm{b}^x-1}{x}\right)+\lim _{x \rightarrow 0}\left(\frac{\mathrm{c}^x-1}{x}\right) \\ & =\log \mathrm{a}+\log \mathrm{b}+\log \mathrm{c} \\ & =\log \left(\lim _{x \rightarrow 0} \frac{\mathrm{a}^x-1}{x}=\log \mathrm{a}\right] \\ & \quad \text { }\end{aligned}$
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Question 82 Marks
Evaluate the following Limits:

$\lim _{x \rightarrow a} \frac{(x+2)^{\frac{5}{3}}-(a+2)^{\frac{5}{3}}}{x-a}$

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Question 102 Marks
Evaluate the following:

$\lim _{x \rightarrow 0}\left[\frac{15^x-5^x-3^x+1}{x^2}\right]$

Answer
$\begin{aligned} & \lim _{x \rightarrow 0} \frac{15^x-5^x-3^x+1}{x^2} \\ & =\lim _{x \rightarrow 0} \frac{5^x \cdot 3^x-5^x-3^x+1}{x^2} \\ & =\lim _{x \rightarrow 0} \frac{5^x\left(3^x-1\right)-1\left(3^x-1\right)}{x^2} \\ & =\lim _{x \rightarrow 0} \frac{\left(3^x-1\right)\left(5^x-1\right)}{x^2 \text { }} \\ & =\lim _{x \rightarrow 0}\left(\frac{3^x-1}{x} \times \frac{5^x-1}{x}\right) \\ & =\lim _{x \rightarrow 0} \frac{3^x-1}{x} \times \lim _{x \rightarrow 0} \frac{5^x-1}{x} \\ & =\log 3 \cdot \log 5 \\ & \cdots\left[\lim _{x \rightarrow 0} \frac{\mathrm{a}^x-1}{x}=\log \mathrm{a}\right] \\ & \end{aligned}$
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Question 152 Marks
Evaluate the following limits:

$\lim _{y \rightarrow 0}\left[\frac{\sqrt{1-y^2}-\sqrt{1+y^2}}{y^2}\right]$

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Question 192 Marks
Evaluate the following limits:

$\lim _{z \rightarrow a}\left[\frac{(z+2)^{\frac{3}{2}}-(a+2)^{\frac{3}{2}}}{z-a}\right]$

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Question 202 Marks
Evaluate the following limits:

If $\lim _{x \rightarrow 5}\left[\frac{x^k-5^k}{x-5}\right]=500$, find all possible values of $\mathrm{k}$.

Answer
$\begin{array}{ll} & \lim _{x \rightarrow 5} \frac{x^{\mathrm{k}}-5^{\mathrm{k}}}{x-5}=500 \\ \therefore \quad & \mathrm{k}(5)^{\mathrm{k}-1}=500 \quad \ldots\left[\because \lim _{x \rightarrow \mathrm{a}} \frac{x^{\mathrm{n}}-\mathrm{a}^{\mathrm{n}}}{x-\mathrm{a}}=\mathrm{na}^{\mathrm{n}-1}\right] \\ \therefore \quad & \mathrm{k}(5)^{\mathrm{k}-1}=4 \times 125 \quad \text { } \\ \therefore \quad & \mathrm{k}(5)^{\mathrm{k}-1}=4 \times(5)^3 \\ \therefore \quad & \mathrm{k}(5)^{\mathrm{k}-1}=4 \times(5)^{4-1} \\ & \text { Comparing both sides, we get } \\ & \mathrm{k}=4\end{array}$
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Question 212 Marks
Evaluate the following limits:

$\lim _{x \rightarrow 7}\left[\frac{(\sqrt[3]{x}-\sqrt[3]{7})(\sqrt[3]{x}+\sqrt[3]{7})}{x-7}\right]$

Answer
$\begin{aligned}
& \lim _{x \rightarrow 7}\left[\frac{(\sqrt[3]{x}-\sqrt[3]{7})(\sqrt[3]{x}+\sqrt[3]{7})}{x-7}\right] \\
& =\lim _{x \rightarrow 7}\left[\frac{\left(x^{\frac{1}{3}}-7^{\frac{1}{3}}\right)\left(x^{\frac{1}{3}}+7^{\frac{1}{3}}\right)}{x-7}\right] \\
& =\lim _{x \rightarrow 7}\left[\frac { x ^ { \frac { 2 } { 3 } } - 7 ^ { \frac { 2 } { 3 } } } { x - 7 } \left[\begin{array}{c}
\text { } \\
\ldots\left[\because(\mathrm{a}-\mathrm{b})(\mathrm{a}+\mathrm{b})=\mathrm{a}^2-\mathrm{b}^2\right]
\end{array}\right.\right. \\
& =\frac{2}{3}(7)^{\frac{-1}{3}} \quad \ldots\left[\because \lim _{x \rightarrow \mathrm{a}} \frac{x^n-\mathrm{a}^n}{x-\mathrm{a}}=\mathrm{na}^{\mathrm{n}-1}\right] \\
& =\frac{2}{3} \cdot \frac{1}{7^{\frac{1}{3}}}=\frac{2}{3 \sqrt[3]{7}} \text { }
\end{aligned}$
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Solve the Following Question.(2 Marks) - Maths (commerce) STD 11 Commerce / Arts Questions - Vidyadip