Soal-Soal Tentang Limit Fungsi

2:25:00 PM
Berikut ini saya mencoba memposting soal-soal tentang Limit fungsi. Sederhana saja kok soalnya. Mudah-mudahan dapat digunakan sebagai bahan latihan
Nilai dari ${\displaystyle \lim_{x\to2}\frac{x^{2}-4}{x^{2}-2x}=\cdots}$

Pembahasan :
\begin{eqnarray*}
\lim_{x\to2}\frac{x^{2}-4}{x^{2}-2x} & = & \lim_{x\to2}\frac{\left(x-2\right)\left(x+2\right)}{x\left(x-2\right)}\\
& = & \lim_{x\to2}\frac{x+2}{x}\\
& = & \frac{4}{2}\\
& = & 2
\end{eqnarray*}
${\displaystyle \lim_{x\to\infty}\frac{3x^{2}-2x+1}{\left(2x-3\right)^{2}}=\cdots}$

Pembahasan :

\begin{eqnarray*}\lim_{x\to\infty}\frac{3x^{2}-2x+1}{\left(2x-3\right)^{2}} & = & \lim_{x\to\infty}\frac{3x^{2}-2x+1}{4x^{2}-12x+9}\\
& = & \lim_{x\to\infty}\frac{3-\frac{2}{x}+\frac{1}{x^{2}}}{4-\frac{12}{x}+\frac{9}{x^{2}}}\\
& = & \frac{3-0+0}{4-0+0}\\
& = & \frac{3}{4}
\end{eqnarray*}
${\displaystyle \lim_{x\to\infty}\left(\sqrt{x^{2}+3x-1}-\sqrt{x^{2}-5x+2}\right)=\cdots}$

Pembahasan :

\begin{eqnarray*}
& = & \lim_{x\to\infty}\left(\sqrt{x^{2}+3x-1}-\sqrt{x^{2}-5x+2}\right)\times\frac{\left(\sqrt{x^{2}+3x-1}+\sqrt{x^{2}-5x+2}\right)}{\left(\sqrt{x^{2}+3x-1}+\sqrt{x^{2}-5x+2}\right)}\\
& = & \lim_{x\to\infty}\frac{\left(x^{2}+3x-1-\left(x^{2}-5x+2\right)\right)}{\sqrt{x^{2}+3x-1}+\sqrt{x^{2}-5x+2}}\\
& = & \lim_{x\to\infty}\frac{\left(x^{2}+3x-1-x^{2}+5x-2\right)}{\sqrt{x^{2}+3x-1}+\sqrt{x^{2}-5x+2}}\\
& = & \lim_{x\to\infty}\frac{\left(8x-3\right)}{\sqrt{x^{2}+3x-1}+\sqrt{x^{2}-5x+2}}\\
& = & \lim_{x\to\infty}\frac{\left(8-\frac{3}{x}\right)}{\sqrt{1+\frac{3}{x}-\frac{1}{x^{2}}}+\sqrt{1-\frac{5}{x}+\frac{2}{x^{2}}}}\\
& = & \frac{8-0}{\sqrt{1+0-0}+\sqrt{1-0+0}}\\
& = & \frac{8}{2}\\
& = & 4
\end{eqnarray*}

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