Question

TOLONG DIJAWAB !!
Diketahui rumus fungsi f(x) = x kuadrat + 2x - 1 .
a. Tentukan daerah hasil fungsi f ! b. Tentukan nilai f(5) dan f(-5) ! c. Tentukan x sehingga f(x) = 1 !

Answer 1

Kategori soal : matematika - fungsi kuadrat
Kelas : 10 sma
Pembahasan : jawaban terlampir

Answer 2

Y = f(x) = x^2 + 2x - 1
a = 1, b = 2, c = -1

a) y = ?
sumbu simetri = -b/2a = -2/2 = -1
y = (-1)^2 + 2 . (-1) - 1 = -2

b) f(5) dan f(-5) ?
f(5) = 5^2 + 2 . 5 - 1 = 34
f(-5) = (-5)^2 + 2 . (-5) - 1 = 14

c) f(x) = 1
x^2 + 2x - 1 = 1
x^2 + 2x - 2 = 0
x12 = (-2 ± akar (2^2 - 4 . 1 . (-2))/(2 . 1)
x12 = (-2 ± akar 12)/2
x12 = (-2 ± 2 akar 3)/2
x1 = (-1 + akar 3)
x2 = (-1 - akar 3)