jika fungsi fx=-2x^2-(a+1)x+2a mempunnyai nilai maksimum 8 maka nilai a=

f(x) = -2x² - (a + 1)x + 2a
a = -2
b = -a - 1
c = 2a

cara 1
[tex]x = - \frac{ b}{2a} [/tex]
[tex]8 = - \frac{ - (a + 1)}{2( - 2)} \\ 8 = \frac{(a + 1)}{ - 4} \\ 8( - 4) = (a + 1 \\ - 32 = a + 1 \\ a = -32 - 1 \\ a = - 33[/tex]
cara 2 (menggunakan turunan)
f(x) = -2x² - (a + 1)x + 2a
f' (x) = -4x - (a + 1)
0 = -4x - (a + 1)
nilai max = 8 sehingga diperoleh
0 = -4(8) - (a + 1)
0 = -32 - a - 1
a = -32 - 1
a = -33

maka nilai a = -33