Fungsi f ditentukan dengan rumus f(x) = ax + b. Bila f(2) = 1 dan f(4) = 7, maka nilai a + 2b adalah Jawab menggunakan caranya

ralat... 7=4.3 +b
-b = 12-7
-b = 5
b = -5

a + 2b
= 3 + 2(-5)
= 3+-10
=3-10
= -7

f(x) = ax+b

f(2)= a(2)+b =1
f(4)= a(4)+b =7

2a+b = 1
4a+b =7
_______ -
-2a =-6
a = 3

2a+b = 1
2(3)+b =1
6+b =1
b = 1-6
b = -5

nilai a+2b = 3+2(-5) =
3-10= -7