Exercise Zone : Limit

Berikut ini adalah kumpulan soal dan pembahasan mengenai limit tipe standar. Jika ada jawaban yang salah, mohon dikoreksi melalui komentar. Terima kasih.

Tipe:


No. 1

\displaystyle\lim_{x\to3}\dfrac{3-\sqrt{2x+3}}{x-3}= ....
CARA 1
limx332x+3x3=limx332x+3x33+2x+33+2x+3=limx39(2x+3)(x3)(3+2x+3)=limx392x3(x3)(3+2x+3)=limx362x(x3)(3+2x+3)=limx32(x3)(x3)(3+2x+3)=limx323+2x+3=23+2(3)+3=23+6+3=23+9=23+3=26=13

CARA 2
limx332x+3x3=limx30222x+310=limx3(12x+3)=12(3)+3=16+3=19=13

No. 2

\displaystyle\lim_{x\to3}\dfrac{\left(\sqrt{x-1}-\sqrt{5-x}\right)\left(\sqrt{4x-3}-1\right)}{x^2-9}=....
  1. -\dfrac16\sqrt2
  2. -\dfrac14\sqrt2
  3. -\dfrac12\sqrt2
  1. \dfrac16\sqrt2
  2. \dfrac12\sqrt2
limx3(x15x)(4x31)x29=limx3(x15x)(4x31)x29x1+5xx1+5x=limx3((x1)(5x))(4x31)(x29)(x1+5x)=limx3(x15+x)(4x31)(x29)(x1+5x)=limx3(2x6)(4x31)(x29)(x1+5x)=limx32(x3)(4x31)(x+3)(x3)(x1+5x)=limx32(4x31)(x+3)(x1+5x)=2(4(3)31)(3+3)(31+53)=2(91)(3+3)(2+2)=2(31)(6)(22)=26(2)=13222=1322=162

No. 3

\displaystyle\lim_{x\to2}\left(\dfrac6{x^2-x-2}-\dfrac2{x-2}\right)= ....
limx2(6x2x22x2)=limx2(6(x2)(x+1)2x2)=limx262(x+1)(x2)(x+1)=limx262x2(x2)(x+1)=limx22x+4(x2)(x+1)=limx22(x2)(x2)(x+1)=limx22x+1=22+1=23

No. 4

\displaystyle\lim_{x\to-2}\dfrac{x^3-x^2-2x+8}{x^3+8}= ....
Ganesha Operation

CARA 1 : PEMFAKTORAN

limx2x3x22x+8x3+8=limx2(x+2)(x23x+4)(x+2)(x22x+4)=limx2x23x+4x22x+4=(2)23(2)+4(2)22(2)+4=4+6+44+4+4=1412=76


CARA 2 : L'HOPITAL

limx2x3x22x+8x3+8=limx23x22x23x2=3(2)22(2)23(2)2=12+4212=1412=76

No. 5

Diketahui fungsi g kontinu di x=2 dan \displaystyle\lim_{x\to2}g(x)=4. Nilai \displaystyle\lim_{x\to2}\left(g(x)\dfrac{x-2}{\sqrt{x}-\sqrt2}\right) adalah ....
Ganesha Operation
limx2(g(x)x2x2)=limx2(g(x)x2x2x+2x+2)=limx2(g(x)(x2)(x+2)x2)=limx2(g(x)(x+2))=4(2+2)=4(22)=82

No. 5

Tentukan nilai dari \displaystyle\lim_{x\to5}\dfrac{x^2-25}{\sqrt{x^2+24}-7}!
Ganesha Operation

CARA 1 : KALIKAN DENGAN SEKAWAN

limx5x225x2+247=limx5x225x2+247x2+24+7x2+24+7=limx5(x225)(x2+24+7)x2+2449=limx5(x225)(x2+24+7)x225=limx5(x2+24+7)=52+24+7=25+24+7=49+7=7+7=14

CARA 2 : L'HOPITAL

limx5x225x2+247=limx52x2x2x2+24=limx52x2+24=252+24=225+24=249=2(7)=14

No. 6

Tentukan nilai dari \displaystyle\lim_{x\to2}\dfrac{x^3+2x^2-4x-8}{x^3-8}!
Ganesha Operation

CARA 1 : PEMFAKTORAN

212-4-8
288
1440
2100-8
248
1240
limx2x3+2x24x8x38=limx2(x2)(x2+4x+4)(x2)(x2+2x+4)=22+4(2)+422+2(2)+4=4+8+44+4+4=1612=43

CARA 2 : L'HOPITAL

limx2x3+2x24x8x38=limx23x2+4x43x2=3(2)2+4(2)43(2)2=3(4)+843(4)=12+412=1612=43

No. 7

Jika f(x)=\cos\left(\dfrac12x\right), maka \displaystyle\lim_{h\to0}\dfrac{f\left(x+\dfrac{h}2\right)-2f(x)+f\left(x-\dfrac{h}2\right)}{h^2}= ....
  1. \dfrac12\sin2x
  2. -\dfrac1{16}\cos\dfrac12x
  3. -\dfrac1{16}\sin\dfrac12x
  1. \dfrac1{16}\cos2x
  2. -\dfrac1{16}\sin2x

CARA 1

limh0f(x+h2)2f(x)+f(xh2)h2=limh0cos12(x+h2)2cos12x+cos12(xh2)h2=limh0cos(12x+h4)2cos12x+cos(12xh4)h2=limh0cos12xcosh4sin12xsinh42cos12x+cos12xcosh4+sin12xsinh4h2=limh02cos12xcosh42cos12x+cos12xcosh4h2=limh02cos12x(cosh41)h2=limh02cos12x(12sin2h81)h2=limh04cos12xsin2h8h2=limh0(4cos12x)sinh8hsinh8h=4cos12x1818=116cos12x

CARA 2 : L'HOPITAL

f(x)=12sin12xf(x)=14cos12x

limh0f(x+h2)2f(x)+f(xh2)h2=limh012f(x+h2)0+(12)f(xh2)2h=limh012f(x+h2)12f(xh2)2h=limh014f(x+h2)+14f(xh2)2=14f(x+02)+14f(x02)2=14f(x)+14f(x)2=12f(x)2=14f(x)=14(14cos12x)=116cos12x

No. 8

f(x)=x^2+2x
\displaystyle\lim_{h\to0}\dfrac{f(x-2h)-f(x)}{4h}=
limh0f(x2h)f(x)4h=limh0(x2h)2+2(x2h)(x2+2x)4h=limh0x24xh+4h2+2x4hx22x4h=limh04xh+4h2+4h4h=limh0(x+h+1)=x+01=x1

No. 9

Jika f(x)=\dfrac{x-\sqrt{x}}{x+\sqrt{x}}, maka \displaystyle\lim_{x\to0}f(x)=
  1. 0
  2. -\dfrac12
  3. -1
  1. -2
  2. \infty

CARA BIASA : KALI SEKAWAN

limx0f(x)=limx0xxx+xxxxx=limx0x22xx+xx2x=limx0x(x2x+1)x(x1)=limx0x2x+1x1=020+101=11=1

CARA L'HOPITAL

limx0f(x)=limx0xxx+x=limx0112x1+12x2x2x=limx02x12x+1=20120+1=11=1

No. 10

\displaystyle\lim_{x\to2}(3x+2)= ....
  1. 4
  2. 5
  3. 6
  1. 7
  2. 8
limx2(3x+2)=3(2)+2=6+2=8

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