Matematika

Pertanyaan

1.limit x mendekati 0 untuk x - sin 2x / 2x + Tan x =…
2.limit x mendekati phi untuk 1 + cos x / sin 2x =…

2 Jawaban

  • jawab

    limit  (x - sin 2x) / (2x + tan x)
    x→0

    limit  (x/2x - sin 2x/2x) / (2x/2x + tan x/2x)
    x → 0
    = (1/2 - 1) / (1+ 1/2)
    = (1 -2)/(2 +1)
    = -1/3

    2.
    limit  (1+ cos x) / (sin 2x)
    x→ π
    =  ( - sin x) / (2 cos 2x)
    = ( - sin π )/ (2 cos 2π)
    =  0
  • [tex]
    \text{1. }
    \text{Menggunakan Dalil l'Hopital}\\
    \lim_{x\to 0}{\frac{x-\sin{2x}}{2x+\tan{x}}}\\
    =\lim_{x\to 0}{\frac{1-2\cos{2x}}{2+\sec^2{x}}}\\
    =\frac{1-2\cos{(2\cdot0)}}{2+\sec^2{0}}\\
    =\frac{1-2}{2+1}\\
    =-\frac{1}{3}\\
    \\
    \text{2. }
    \text{Mengalikan dengan bentuk sekawan}\\

    \lim_{x\to\pi}{\frac{1+\cos{x}}{\sin{2x}}\cdot\frac{1-\cos{x}}{1-\cos{x}}}\\
    =\lim_{x\to\pi}{\frac{1-\cos^2{x}}{\sin{2x}\cdot(1-\cos{x})}}\\
    =\lim_{x\to\pi}{\frac{\sin^2{x}}{2\sin{x}\cos{x}\cdot(1-\cos{x})}}\\
    =\lim_{x\to\pi}{\frac{\sin{x}}{2\cos{x}\cdot(1-\cos{x})}}\\
    =\frac{\sin{\pi}}{2\cos{\pi}\cdot(1-\cos{\pi})}\\
    =\frac{0}{2\cdot(-1)\cdot(1-(-1))}\\
    =\frac{0}{-4}\\
    =0
    [/tex]

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