jika f(x)=nx²-4x+n+2 mempunyai nilai minimum -1 maka nilai n?

Xmin = -b/2a = -(-4)/2n = 4/2n = 2/n

fmin = f(2/n)
f(2/n) = -1
n(2/n)^2 - 4(2/n) + n + 2 = -1
4/n - 8/n + n + 3 = 0
-4/n + n + 3 = 0
-4 + n^2 + 3n = 0
n^2 + 3n - 4 = 0
n^2 - n + 4n - 4 = 0
n(n - 1) + 4(n - 1) = 0
(n - 1)(n + 4) = 0
n-1 = 0
n = 1

n+4 = 0
n = -4

karna nilai ekstremnya minimum maka nilai yg memenuhi n > 0
dan n = 1