1) F(x) = 4x² - 5
F’(x) = 8x
A. Titik Stasioner
F’(x) = 0
8x = 0
x = 0
y = F(x)
y = 4x² - 5
y = 4(0)² - 5
= -5
Jadi ( x , y ) : ( 0 , -5 )
B. Interval Fungsi Turun
F’(x) < 0
8x < 0
x < 0
C. Interval fungsi Naik
F’(x) > 0
8x > 0
x < 0
Grafik Fungsinya :
2) F(x) = 2x³ + x² - 6x
F’(x) = 6x² - 6
A. Titik Stasioner
F’(x) = 0
6x² - 6 = 0
6x² = 6
x² = 1
x = 1 V x = -1
B. Interval Fungsi Turun
F’(x) < 0
6x² - 6 < 0
6x² < 6
x² < 1
-1 < x <1
C. Interval Fungsi Naik
F’(x) > 0
6x² - 6 > 0
6x² > 6
x² > 1
x > 1 atau x < -1
Grafik Fungsinya :
3) F(x) = 2x4 – 12x³
F’(x) = 8x³ - 36x²
A. Titik Stasioner
F’(x) = 0
8x³ - 36x² = 0
4x² ( 2x – 9 ) = 0
4x² = 0
x² = 0
x = 0
atau
2x – 9 = 0
2x = 9
x = 9/2
B. Interval Fungsi Naik
F’(x) > 0
8x³ - 36x² > 0
4x² ( 2x – 9 ) > 0
4x² < 0
x² < 0
x < 0
atau
2x – 9 > 0
2x > 9
x > 9/2
C. Interval Fungsi Turun
F’(x) < 0
8x³ - 36x² < 0
4x² ( 2x – 9 ) < 0
4x² < 0
x² < 0
x < 0
atau
2x – 9 < 0
2x < 9
x < 9/2
0 < x < 9/2
Grafik Fungsinya :
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