sebuah fungsi dirumuskan dengan f(x) = x² + bx + c jika f(1) = 4 , dn f(-3) = 8 , tentukan : a. nilai b + c. b. nilai f(5) di bantu

Semoga membantu, maaf kalo engga jelas, soale udah malem

f(x) = x² + bx + c
f(1) = (1)² + b(1) + c = 4
f(1) = 1 + b + c = 4
f(1) = b + c = 4 - 1
f(1) = b + c = 3....(1)

f(-3) = (-3)² + b(-3) + c = 8
f(-3) = 9 + -3b + c = 8....
f(-3) = -3b + c = 8-9
f(-3) = -3b + c = -1...(2)

b + c = 3
-3b + c = -1
------------------ –
4b = 4
b = 4/4
b = 1

b = 1 disubstisusikan ke b + c = 3, diperoleh :
1 + c = 3
c = 3 - 1
c = 2

a) Nilai b + c = 1 + 2 = 3
b)
Jadi,
f(x) = x² + x + 2
f(5) = 5² + 5 + 2
f(5) = 25 + 5 + 2
f(5) = 32

Semoga membantu, maaf kalau ada yang salah.