nomor 12 soalnya nnti dikumpulkan

f(2) = 2
2a +b = 2
b = 2 - 2a

f(4) = 10
4a + b = 10

4a + b = 10
4a + 2 - 2a = 10
2a = 10 - 2
2a = 8
a = 4

b = 2 - 2a
b = 2 - 8
b = -6

3a + 5b = 12 - 30 = -18 [B]

2a+b=2
4a+b=10

a=4 dan b=-6
3a+5b=3(4)+5(-6)= -18
hasilnya -18