Posted by andi telaumbanua on Feb 17, 2018 in
Matematika
Find the first derivative from
x^y = y^x
Answare:
Use logarithmic derivative to find the first derivative this function
ln x^y = ln y^x
y ln x = x ln y
y = (x lny) / lnx
so:
d/dx (x ln y) = d/dx (x) ln y + x d/dx (ln y)
= ln y + x [d/dy (ln y) dy/dx]
= ln y + x ( 1/y) dy/dx
= ln y + x/y dy/dx
So:
y = (x lny) / ln x
dy/dx = [ d/dx(x lny) ln x – x ln y d/dx (ln x) ] / (ln x)^2
dy/dx = [ ( ln y + x/y dy/dx) ln x – x ln y 1/x] / (ln x)^2
dy/dx = [ ln y ln x + lnx ( x/y) dy/dx – ln y ] / (ln x)^2
ln^2 x dy/dx = ln y ln x + lnx ( x/y) dy/dx – ln y
ln^2 x dy/dx – x/y ln x dy/dx = ln y ln x – ln y
dy/dx (ln^2 x – x/y lnx ) = ln y (lnx – 1)
dy/dx = [ln y ln (x-1)] / [ln^2 x – x/y ln x]
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Posted by andi telaumbanua on Feb 17, 2018 in
Matematika
Tentukanlah integral dari:
-
∫ sin 2x cos 3x dx
-
∫ sin^2 3x cos 3x dx
Jawab:
1. ∫ sin ax cos bx dx = -1 /2 [ cos(a-b)x / (a-b) + (cos ( a+b)x) /(a+b)] + C
Maka:
∫ sin 2x cos 3x dx = -1 /2 [ cos(2-3)x /(2-3) + (cos ( 2+3)x) /(2+3)] + C
∫ sin 2x cos 3x dx = – 1 /2 [ cos(-x) /(-1) + (cos 5x) /5 ] + C
∫ sin 2x cos 3x dx = -cos 5x /10 + cosx /2 + C
2. Misalkan: u = sin 3x
Maka: du/dx = 3 cos3x
Sehingga: dx = du /(3 cos3x )
∫ sin^2 3x cos 3x dx = ∫ u^2 cos 3x (du/3 cos 3x )
∫ sin^2 3x cos 3x dx = 1 /3 ∫u^2 du
∫ sin^2 3x cos 3x dx = 1/3 1/3 u^3 + C
∫ sin^2 3x cos 3x dx = 1/9 (sin 3x)^3 + C
∫ sin^2 3x cos 3x dx = 1/9 sin^3 3x + C
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Posted by andi telaumbanua on Feb 17, 2018 in
Matematika
Tentukanlah Integral dari :
∫ sin^4 x cos^3 x dx
Jawab:
Misalkan: u = sin x
Maka: du/dx = cosx
Sehingga: dx = du/cosx
∫ sin^4 x cos^3 x dx = ∫u^4 cos^3 x du/cosx
∫ sin^4 x cos^3 x dx = ∫ u^4 cos^3 x (du/cos x)
∫ sin^4 x cos^3 x dx = ∫ u^4 cos^2 x du
Karena: cos^2 x = 1 – sin^2 x
Maka:
∫ sin^4 x cos^3 x dx = ∫ u^4 (1- sin^2 x) du
Karena: u = sin x
Maka:
∫ sin^4 x cos^3 x dx = ∫ u^4 (1- u^2) du
∫ sin^4 x cos^3 x dx = ∫ (u^4- u^6) du
∫ sin^4 x cos^3 x dx = 1 /(4+1) u^(4+1) – 1 /(6+1) u^(6+1) + C
∫ sin^4 x cos^3 x dx = 1 /5 u^5 – 1 /7 u^7 + C
∫ sin^4 x cos^3 x dx = 1 /5 sin^5 x – 1 /7 sin^7 x + C
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Posted by andi telaumbanua on Feb 17, 2018 in
Matematika
Tentukanlah integral dari : ∫ sin^4 x dx
Jawab:
∫ sin ^n u du = – (sin^(n-1) u cosu) /n + (n-1) /n ∫ sin^(n-2) u du + c
Maka:
∫ sin^4 x dx = – (sin^(4-1) x cosx) /4 + (4-1)/4 ∫ sin^(4-2) x dx
∫ sin^4 x dx = – (sin^3 x cosx) /4 + 3/4 ∫ sin^2 x dx
∫ sin^4 x dx = – (sin^3 x cosx) /4 + 3/4 [- (sin^(2-1) x cosx) /2 + (2-1)/2 ∫ sin^(2-2) x dx ]
∫ sin^4 x dx = – (sin^3 x cosx) /4 + 3/4 [- (sin^1 x cosx) /2 + 1/2 ∫ sin^0 x dx ]
∫ sin^4 x dx = – (sin^3 x cosx) /4 + 3/4 [- (sin x cosx)/2 + 1/2 ∫ dx ]
∫ sin^4 x dx = – ( sin^3 x cosx) /4 + 3/4 [- (sin x cosx)/2+1/2 (x) ] + C
∫ sin^4 x dx = – (sin^3 x cosx) /4 – (3 sin x cosx) / 8 + (3 x) / 8 + C
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Posted by andi telaumbanua on Feb 17, 2018 in
Matematika
Tentukanlah integral dari : ∫ cos^4 x dx
Jawab:
∫cos ^n u du = (cos^(n-1) u sin u) / n + (n-1) /n ∫ cos^(n-2) u du + c
Maka:
∫ cos^4 x dx = (cos^3 x sin x) /4 + (4-1) /4 ∫ cos^2 x dx
∫ cos^4 x dx = (cos^3 x sin x) /4 + 3/4 ( ( cos x sin x) /2 + (2-1)/2 ∫ (cosx)^(2-2) dx )
∫ cos^4 x dx = (cos^3 x sin x) /4 + 3/4 ( ( cos x sin x) /2 + 1/2 ∫ (cosx)^0 dx )
∫ cos^4 x dx = (cos^3 x sin x) /4 + 3/4 ( ( cos x sin x) /2 + 1/2 ∫ dx )
∫ cos^4 x dx = (cos^3 x sin x) /4 + 3/4 (( cos x sin x) /2 + 1/2 (x) ) + C
∫ cos^4 x dx = (cos^3 x sin x) /4 + ( 3 cos x sin x) /8 + 3/8 x + C
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