16.
17. f(x) = x³ + ax² + bx + c
f(x) turun pada interval -2 < x < 5
maka,
f'(x) = 3x²+2ax+b <0
x1 =-2 atau x2 =5
1) x1+x2 = -b/a
-2+5 = -2a/3
3 = -2a/3
9 = -2a
-9/2 = a
2) x1. x2 = c/a
(-2)(5) = b/3
-10 = b/3
-30 = b
Maka,
4a + b
= 4(-9/2)+(-30)
= (-18)-30
= -48 (A)
Mapel: Matematika
Kelas: 11
Materi: Limit dan Turunan
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16.
17. f(x) = x³ + ax² + bx + c
f(x) turun pada interval -2 < x < 5
maka,
f'(x) = 3x²+2ax+b <0
x1 =-2 atau x2 =5
1) x1+x2 = -b/a
-2+5 = -2a/3
3 = -2a/3
9 = -2a
-9/2 = a
2) x1. x2 = c/a
(-2)(5) = b/3
-10 = b/3
-30 = b
Maka,
4a + b
= 4(-9/2)+(-30)
= (-18)-30
= -48 (A)
Mapel: Matematika
Kelas: 11
Materi: Limit dan Turunan