Qus : 2 nimcet PYQ 1 $\lim _{{x}\rightarrow1}\frac{{x}^4-1}{x-1}=\lim _{{x}\rightarrow k}\frac{{x}^3-{k}^2}{{x}^2-{k}^2}=$, then find k
1 8/3 2 4/3 3 2/3 4 1 Go to Discussion nimcet Previous Year PYQ nimcet NIMCET 2023 PYQ Solution
Quick DL Method Solution
Given:
\[
\lim_{x \to 1} \frac{x^4 - 1}{x - 1}
= \lim_{x \to k} \frac{x^3 - k^2}{x^2 - k^2}
\]
LHS using derivative:
\[
\lim_{x \to 1} \frac{x^4 - 1}{x - 1} = \left.\frac{d}{dx}(x^4)\right|_{x=1} = 4x^3|_{x=1} = 4
\]
RHS using DL logic:
\[
\lim_{x \to k} \frac{x^3 - k^2}{x^2 - k^2}
\approx \frac{3k^2(x - k)}{2k(x - k)} = \frac{3k}{2}
\]
Equating both sides:
\[
\frac{3k}{2} = 4 \Rightarrow k = \frac{8}{3}
\]
\[
\boxed{k = \frac{8}{3}}
\]
Qus : 4 nimcet PYQ 4 $\lim_{x\to3} \dfrac{\sqrt{3x}-3}{\sqrt{2x-4}-\sqrt{2}}$ is equal to
1 $\sqrt{3}$ 2 $\frac{\sqrt{3}}{2}$ 3 $\frac{1}{2\sqrt{2}}$ 4 $\frac{1}{\sqrt{2}}$ Go to Discussion nimcet Previous Year PYQ nimcet NIMCET 2019 PYQ Solution
Rationalize numerator and denominator:
\[
\frac{\sqrt{3x}-3}{\sqrt{2x-4}-\sqrt{2}}
=\frac{\dfrac{3(x-3)}{\sqrt{3x}+3}}{\dfrac{2(x-3)}{\sqrt{2x-4}+\sqrt{2}}}
=\frac{3}{\sqrt{3x}+3}\cdot\frac{\sqrt{2x-4}+\sqrt{2}}{2}.
\]
Now let \(x\to 3\): \(\sqrt{3x}\to 3\) and \(\sqrt{2x-4}\to \sqrt{2}\). Hence
\[
\lim_{x\to 3}=\frac{3}{3+3}\cdot\frac{\sqrt{2}+\sqrt{2}}{2}
=\frac{1}{2}\cdot\sqrt{2}=\boxed{\frac{1}{2\sqrt{2}}}.
\]
Qus : 9 nimcet PYQ 3 The value of ${{Lt}}_{x\rightarrow0}\frac{{e}^x-{e}^{-x}-2x}{1-\cos x}$ is equal to
1 2 2 1 3 0 4 -1 Go to Discussion nimcet Previous Year PYQ nimcet NIMCET 2024 PYQ Solution
Evaluate:
$$\lim_{x \to 0} \frac{e^x - e^{-x} - 2x}{1 - \cos x}$$
Step 1: Apply L'Hôpital's Rule (since it's 0/0):
First derivative:
$$\frac{e^x + e^{-x} - 2}{\sin x}$$
Still 0/0 → Apply L'Hôpital's Rule again:
$$\frac{e^x - e^{-x}}{\cos x}$$
Now,
$$\lim_{x \to 0} \frac{1 - 1}{1} = 0$$
Final Answer:
$$\boxed{0}$$
Qus : 11 nimcet PYQ 1 Let f(x) be a polynomial of degree four, having extreme value at x = 1 and x = 2. If $\lim _{{x}\rightarrow0}[1+\frac{f(x)}{{x}^2}]=3$, then f(2) is
1 0 2 4 3 - 8 4 - 4 Go to Discussion nimcet Previous Year PYQ nimcet NIMCET 2017 PYQ Solution Given it has extremum values at x=1 and x=2
⇒f′(1)=0 and f′(2)=0
Given f(x) is a fourth degree polynomial
Let $f(x)=a{x}^4+b{x}^3+c{x}^2+dx+e$
Given
$\lim _{{x}\rightarrow0}[1+\frac{f(x)}{{x}^2}]=3$
$\lim _{{x}\rightarrow0}\lbrack1+\frac{a{x}^4+b{x}^3+c{x}^2+\mathrm{d}x+e}{{x}^2}\rbrack=3$
$\lim _{{x}\rightarrow0}\lbrack1+a{x}^2+bx+c+\frac{d}{x}+\frac{e}{{x}^2}\rbrack=3$
For limit to have finite value, value of 'd' and 'e' must be 0
⇒d=0 & e=0
Substituting x=0 in limit
⇒ c+1=3
⇒ c=2
$f^{\prime}(x)=4a{x}^3+3b{x}^2+2cx+d$
$x=1$ and $x=2$ are extreme values,
⇒$f^{\prime}(1)=0$ and $f^{\prime}(2)=0
⇒ $4a+3b+4=0$ and $32a+12b+8=0$
By solving these equations
we get, $a=\frac{1}{2}$ and $b=-2$
So,
$f(x)=\frac{x^{4}}{2}-2x^{3}+2x^{2}$
⇒$f(x)=x^{2}(\frac{x^{2}}{2}-2x+2)$
⇒$f(2)=0$
Qus : 14 nimcet PYQ 4 $\lim_{x\to0} \dfrac{x \tan x}{(1-\cos x)}$
1 1/2 2 -1/2 3 - 2 4 2 Go to Discussion nimcet Previous Year PYQ nimcet NIMCET 2017 PYQ Solution
Given limit is indeterminate of type $\frac{0}{0}$.
(DL Rule) Differentiate numerator and denominator:
$\displaystyle \lim_{x\to0}\frac{x\tan x}{1-\cos x}=\lim_{x\to0}\frac{\tan x+x\sec^2 x}{\sin x}$
As $x\to0$, $\tan x\approx x$, $\sin x\approx x$, $\sec^2 x\approx1$
$\Rightarrow \dfrac{x+x}{x}=2$
Answer: $\boxed{2}$ ✅
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