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d) 
lim_(x rarr0)(e^(x)-e^(-x)-2x)/(x-sin x)

d) limx0exex2xxsinx \lim _{x \rightarrow 0} \frac{e^{x}-e^{-x}-2 x}{x-\sin x}

Full solution

Q. d) limx0exex2xxsinx \lim _{x \rightarrow 0} \frac{e^{x}-e^{-x}-2 x}{x-\sin x}
  1. Plug in x=0x = 0: First, let's try to plug in x=0x = 0 directly and see what happens.\newlinelimx0exex2xxsinx=e0e0200sin0=11000=00\lim_{x \to 0}\frac{e^{x}-e^{-x}-2x}{x-\sin x} = \frac{e^{0}-e^{0}-2\cdot 0}{0-\sin 0} = \frac{1-1-0}{0-0} = \frac{0}{0}\newlineWe get an indeterminate form, so we need to use L'Hôpital's Rule.
  2. Apply L'Hôpital's Rule: L'Hôpital's Rule says that if we have an indeterminate form of 0/00/0 or /\infty/\infty, we can take the derivative of the numerator and the denominator separately and then take the limit.\newlineSo, let's find the derivative of the numerator: ddx(exex2x)=ex+ex2\frac{d}{dx}(e^{x}-e^{-x}-2x) = e^{x} + e^{-x} - 2.
  3. Find derivative of numerator: Now, let's find the derivative of the denominator: ddx(xsinx)=1cosx\frac{d}{dx}(x-\sin x) = 1 - \cos x.
  4. Find derivative of denominator: Now we take the limit of the derivatives: limx0ex+ex21cosx\lim_{x \to 0}\frac{e^{x} + e^{-x} - 2}{1 - \cos x}. Let's plug in x=0x = 0 again: e0+e021cos0=1+1211=00\frac{e^{0} + e^{0} - 2}{1 - \cos 0} = \frac{1 + 1 - 2}{1 - 1} = \frac{0}{0}. Oops, we got another indeterminate form, so we need to apply L'Hôpital's Rule again.

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