Jika f(3x+2) = x(x+1) dan f'x adalah turunan pertama fungsi f, maka 6 f'(11) adalah

f(3x+2) = x² + x
misal 3x + 2 = p
3x = p - 2
x = (p - 2)/3
f(p) = {(p - 2)/3}² + {(p-2)/3}
f(p) = (p² - 4p + 4)/9 + (p - 2)/3
f(p) = (p² - 4p + 4)/9 + 3(p - 2)/3
f(p) = (p² - 4p + 3p + 4 - 6)9
f(p) = (p² - p - 2)/9
f(p) = 1/9p² - 1/9p - 2/9
f(x) = 1/9x² - 1/9x - 2/9
turunan
f'(x) = 2/9 x - 1/9
6 f'(11) = 6( 2.11/9 - 1/9)
= 6(22/9 - 1/9)
= 6(21/9)
= 126/9
= 16