KALKULUS
1.
Y = x2 -25
2.
Y = -x2 + 7x -12
3.
Y =-x2 - 8x +9
4.
Y = -2x2-7x + 4
5.
Y = -x2 + 6x
Jawaban
1. Y = x2 -25
1. Y = x2 -25
Langkah 1
Titik potong sumbu –x ( y = 0)
Y = x2 -25
v0 = x2 - 25
( x – 5 ) ( x + 5)
x = 5 x=
-5
koordinat titik potong sumbu –x (5,0) dan
(-5,0)
Langkah 2
Titik potong sumbu –y( x = 0 )
Y = x2 -25
Y = 0 – 25
Y = -25
koordinat titik potong sumbu –y ( 0, -25)
Langkah 3
Koordinat titik puncak (xp,yp)
xp= -b/2a
xp= -0/2 . 1
xp= -0/2
xp= 0
yp= -b2-4ac / 4a
yp= -02 - 4.1.-25 /4.1
yp= -0 + 100 /4
yp= -25
xp= 7/2
yp= -b2-4ac / 4a
yp= -7^2-4.-1. -12/ 4.-1
yp= -49-48 / -4
yp= 97 / 4
koordinat titik puncak (xp,yp) ( 7/2, 97/4 )
3. Y =-x2 - 8x +9
Y = 9
4. Y = -2x2-7x + 4
0 = -2x2-7x + 4
2x2+7x - 4 = 0
1/2 (2x + 8) ( 2 x – 1 )
xp= -0/2 . 1
xp= -0/2
xp= 0
yp= -b2-4ac / 4a
yp= -02 - 4.1.-25 /4.1
yp= -0 + 100 /4
yp= -25
Langkah 1
Titik potong sumbu –x ( y = 0)
Y = -x2 + 7x -12
0 = -x2 + 7x -12
0 = x2 - 7x +12
( x – 4) ( x – 3 )
x = 4 x=
3
koordinat titik potong sumbu –x ( 4,0)
dan ( 3,0 )
Langkah 2
Titik potong sumbu –y( x = 0 )
Y = -x2 + 7x -12
Y = -02 + 0 -12
Y = -12
koordinat titik potong sumbu –y ( 0,-12 )
Langkah 3
Koordinat titik puncak (xp,yp)
xp= -b/2a
xp= -7/2.-1xp= 7/2
yp= -b2-4ac / 4a
yp= -7^2-4.-1. -12/ 4.-1
yp= -49-48 / -4
yp= 97 / 4
koordinat titik puncak (xp,yp) ( 7/2, 97/4 )
3. Y =-x2 - 8x +9
Langkah 1
Titik potong sumbu –x ( y = 0)
Y =-x2 - 8x +9
0 =-x2 - 8x +9
x2 + 8x -9 = 0
( x + 9 ) ( x – 1 )
x = - 9 x = 1
koordinat titik potong sumbu –x ( - 9,0 )
dan ( 1,0)
Langkah 2
Titik potong sumbu –y( x = 0 )
Y =-x2 - 8x +9
0 =-02 - 0 +9Y = 9
koordinat titik potong sumbu –y ( 0,9)
Langkah 3
Koordinat titik puncak (xp,yp)
xp= -b/2a
xp= -(-8) /2.-1
xp= -4
yp= -b2-4ac / 4a
yp= -(-8)^2-4.-1. 9/ 4.-1
yp= -64+36 / -4
yp= -100 / -4
yp= 25
4. Y = -2x2-7x + 4
Langkah 1
Titik potong sumbu –x ( y = 0)
Y = -2x2-7x + 40 = -2x2-7x + 4
2x2+7x - 4 = 0
1/2 (2x + 8) ( 2 x – 1 )
( x + 4 )
( 2 x – 1 )
x = -4 2x = 1
x = 1/2
koordinat titik potong sumbu –x ( -4, 0) dan ( 1/2, 0 )
Langkah 2
Titik potong sumbu –y( x = 0 )
Y = -2x2-7x + 4
Y = 0-0+ 4
Y = 4
koordinat titik potong sumbu –y ( 0,4)
yp= -b2-4ac / 4a
Langkah 3
Koordinat titik puncak (xp,yp)
xp= -b/2a
xp= -(-7)/2.-2
xp= -7/4
yp= -b2-4ac / 4a
yp= -(-7)^2-4.-2.4 / 4.-2
yp= -49+32 / -8
yp= 17/8
5. Y = -x2 + 6x
Langkah 1
Titik potong sumbu –x ( y = 0)
Y = -x2 + 6x
0 = -x2 + 6x
x2 - 6x =0
Y = -x2 + 6x
0 = -x2 + 6x
x2 - 6x =0
x ( x - 6 )
x = 0 x = 6
koordinat titik potong sumbu –x ( 0, 0) dan ( 6, 0 )
x = 0 x = 6
koordinat titik potong sumbu –x ( 0, 0) dan ( 6, 0 )
Langkah 2
Titik potong sumbu –y( x = 0 )
Y = -x2 + 6x
Y = -02 + 0
Y = 0
Y = -x2 + 6x
Y = -02 + 0
Y = 0
Komentar
Posting Komentar