Posted by andi telaumbanua on Feb 11, 2018 in
Matematika
Carilah y^’ dari fungsi xy+2x+3x^2=4 !
Jawab :
Gunakan metode turunan implisit
xy+2x+3x^2=4
y = (4-2x-3x^2)/x
maka:
(d (xy+2x+3x^2 ))/dx = (d(4))/dx
(d( xy))/dx+ d( 2x )/dx+ (d(3x^2))/dx = (d( 4))/dx
[(d( x)/dx)(y)+ (x)(d(y)/dx) ]+ d( 2x )/dx+ (d(3x^2))/dx = (d( 4))/dx
y+x d(y)/dx+ 2+ 6x = 0
x d(y)/dx= -(y+2+6x)
dy/dx=-(y+2+6x)/x
maka∶
dy/dx=(-((4-2x-3x^2)/x)-2-6x)/x
dy/dx=((-((4-2x-3x^2)/x)-2-6x)/x) (x/x)
dy/dx=(-4+2x+3x^2-2x-6x^2)/x^2
dy/dx=(-4-3x^2)/x^2
Posted by andi telaumbanua on Feb 11, 2018 in
Matematika
Carilah y^’ dari fungsi x^3+y^3=1 !
Jawab :
Gunakan metode turunan implisit
(d (x^3+y^3 ))/dx = (d( 1))/dx
(d( x^3))/dx+ (d( y^3))/dx = (d( 1))/dx
(d( x^3))/dx+ (d( y^3 )/dy)(dy/dx) = (d( 1))/dx
3x^2 + (3y^2) ( dy/dx) =0
dy/dx= (-3x^2)/(3y^2 )
dy/dx= – x^2/y^2
Posted by andi telaumbanua on Feb 11, 2018 in
Matematika
Carilah y^” dari fungsi x^4+ y^4 = 81 !
Jawab :
Gunakan metode turunan implisit
(d(x^4))/dx + (d(y^4))/dx= ((d(81))/dx
4x^3+(d(y^4 )/dy)(dy/dx )=0
4x^3+ 4y^3 y^’=0
y^’= -x^3/y^3
Maka :
y^”= -((d(x^3 )/dx)(y^3 )-x^3 (d(y^3 )/dx) )/(y^3)^2
y^”= -(3x^2 (y^3 )-x^3 (3y^2 )(y^’))/y^6
y^”= -(3x^2 y^3-x^3 (3y^2 )(-x^3/y^3 ))/y^6
y^”= -(3x^2 y^3+ 3x^6/y)/y^6
y^”=(-(3x^2 y^3+ 3x^6/y)/y^6 )(y/y)
y^”= -(3(x^2 y^4+ x^6) )/y^7
y^”= -(3x^2 (y^4+ x^4) )/y^7
Atau
y^”= -(3x^2 (81) )/y^7 = -243(x^2/y^7 )
Posted by andi telaumbanua on Feb 11, 2018 in
Matematika
Carilah dy/dx dari fungsi sin(x + y) = y^2 cosx !
Jawab :
Gunakan metode turunan implisit
(d (sin(x + y) ))/dx = (d(y^2 cosx ))/dx
cos (x + y) ((d(x+ y))/dx) = ((d(y^2))/dx)(cosx)+(y^2 )((d(cosx))/dx)
cos (x + y) [(d(x)/dx)+(dy/dx)]=(d(y^2 )/dy)(dy/dx)(cosx)+ y^2 (- sin x)
cos (x + y) [ 1+dy/dx]=2y dy/dx(cosx)- y^2 (sin x)
cos (x + y)+ dy/dx cos (x+y) =2y dy/dx(cosx)- y^2 (sin x)
cos (x + y) + y^2 sinx = 2y dy/dx cosx – dy/dx cos (x+y)
cos (x + y) + y^2 sinx = dy/dx[2y cosx-cos (x+y) ]
dy/dx= (cos (x + y) + y^2 sinx)/(2y cosx-cos (x+y) )
Posted by andi telaumbanua on Feb 11, 2018 in
Matematika
(a) Carilah dy/dx dari fungsi x^2+ y^2=25
(b) Tentukan persamaan garis singgungnya di titik (3,4)
Jawab:
(a) Gunakan metode turunan implisit
x^2+ y^2=25
maka∶ y= √(2&25- x^2 )
(d ( x^2+ y^2))/dx = (d( 25))/dx
(d( x^2))/dx+ (d( y^2))/dx = (d( 25))/dx
(d( x^2))/dx+ (d( y^2 )/dy)(dy/dx) = (d( 25))/dx
2x + (2y) ( dy/dx) =0
dy/dx= (-2x)/2y
dy/dx= – x/y
maka: dy/dx= – x/√(2&25- x^2 )
(b) Maka : m = – 3/√(2&25- 3^2 ) = – 3/√(2&16) = – 3/4
Maka persamaan garis singgung kurva dititik (3,4) adalah :
y – y_1=m( x- x_1)
y – 4 = – 3/4 ( x-3)
y = – 3/4 x+ 9/4+ 4
y = – 3/4 x + 25/4
atau 4y = – 3x + 25
atau 3x + 4y = 25