jika diketahui fungsi f(x)=ax+b dengan f(3)=13 dan f(5)=25,maka nilai. dari2a+3b adalah

f(3) = 3a + b = 13
f(5) = 5a + b = 25

5a + b = 25
3a + b = 13
__________ -
2a = 12
a = 12/2
a = 6

3(6) + b = 13
18 + b = 13
b = 13 - 18
b = -5

2a + 3b
= 2(6) + 3(-5)
= 12 - 15
= -3

f(x) = ax + b

f(3) = a(3) + b
13 = 3a + b

f(5) = a(5) + b
25 = 5a + b

eliminasi
5a + b = 25
3a + b = 13 [ - ]
2a = 12
a = 12/2 = 6

13 = 3(6) + b
13 = 18 + b
13-18 = b
b = -5

jadi, 2A +3b = 12 + (-15) = -3