Obtain a maximum value of the function f x x3 -... - JAMB Mathematics 1992 Question
Obtain a maximum value of the function f(x) x3 - 12x + 11
A
-5
B
-2
C
2
D
27
correct option: d
f(x) = x3 - 12x + 11
\(\frac{df(x)}{dx)}\) = 3x2 - 12 = 0
∴ 3x2 - 12 = 0 \(\to\) x2m = 4
x = \(\pm\)2, f(+2) = 8 - 24 + 11 = -15
= f(-2) = (-8) + 24 + 11
= 35 - 8 = 27
∴ maximum value = 27
\(\frac{df(x)}{dx)}\) = 3x2 - 12 = 0
∴ 3x2 - 12 = 0 \(\to\) x2m = 4
x = \(\pm\)2, f(+2) = 8 - 24 + 11 = -15
= f(-2) = (-8) + 24 + 11
= 35 - 8 = 27
∴ maximum value = 27
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