suatu fungsi f(x)=a×+b, jika f(2)=-2 dan f(-3)=13 maka hitunglah nilai dari f(4)+f(5)

f (x) = ax + b

f (2) = -2
2a + b = -2......(pers.1)

f (-3) = 13
-3a + b = 13.....(pers.2)

Eliminasi pers.1 dan 2
2a + b = -2
-3a + b = 13
_________ _
5a = -15
a = -15/5
a = -3

2a + b = -2
2 (-3) + b = -2
-6 + b = -2
b = -2 + 6
b = 4

Rumus f (x)
= ax + b
= -3x + 4

f (4)
= -3 (4) + 4
= -12 + 4
= -8

f (5)
= -3 (5) + 4
= -15 + 4
= -11

Nilai f (4) + f (5)
= -8 + (-11)
= -8 - 11
= -19

f(x) = ax + b

f(2) = -2
f(-3) = 13
maka,


Dimasukkan dan Eliminasi
2a + b = -2 (pers1)
-3a + b = 13 (pers2)
__________ -
5a = -15
a = -15 / 5
a = -3

Masukan 3 ke 1

2a + b = -2
2 . -3 + b = -2
-6 + b = -2
b = -2 + 6
b = 4

maka, Rumus Fungsinya
F(x) = -3x + 4
f (4) = -3 . 4 + 4
f(4) = -12 + 4 = -8

f(5) = -3 . 5 + 4
f(5) = -15 + 4 = -11

f(4) + f(5) =
-8 + -11 = -19