1. fungsi f ditentukan dengan rumus f( × ) = a× +b. bila( f2 ) = 2 dan f( 4 ) = 10, maka nilai 3a + 5b adalah ? pakai cara

f (x) = ax + b
f (2) =2 ==» a.2 + b = 2
2a + b = 2 ==» b = 2 - 2a....1)
f(4) = 10 ==» a.4 + b = 10
4a + b = 10...2) subsitusikan...1) ke.....2)
4a + ( 2 - 2a ) = 10
4a + 2 -2a = 10
2a = 10 - 2
2a = 8
a = 8/2 = 4
dari.....1) b = 2 - 2a
b = 2 -2.4
b = 2 -8
b = -6
3a +5b = 3.4 + 5.-6
' = 12 - 30
= -18