Fungsi f ditentukan oleh f ( x ) = ax + b.
Jika pasangan – pasangan berurutan
(p,–3) , (–3,q) , (r,2) , (2,–2) dan (–2,6)
Adalah anggota dari fungsi itu ,
Nilai dari p , q , dan r adalah .....
a. p = 5 , q = 6 , r = 2
b. p = 3/2 , q = 8 , r = 2
c. p = 5/2 , q = 8 , r = 0
d. p = 3 , q = 6 , r = 3
Jawab :
f ( x ) = ax + b
( 2 , –2 ) dan (–2 , 6 )
f ( 2 ) = ax + b = –2
a . 2 + b = –2
2a + b = –2 ..... ( persamaan 1 )
f (–2 ) = ax + b = 6
a . –2 + b = 6
–2a + b = 6 ..... ( persamaan 2 )
2a + b = –2
–2a + b = 6 –
------------------
2a – (–2a) = –2 – 6
2a + 2a = –8
4a = –8
a = –8 : 4
a = –2
2a + b = –2
2 . –2 + b = –2
–4 + b = –2
b = –2 + 4
b = 2
f ( x ) = ax + b
f ( x ) = –2 . x + 2
f ( x ) = –2x + 2
( p , –3 )
f ( x ) = –2x + 2
f ( p ) = –2x + 2 = –3
–2 . p + 2 = –3
–2p + 2 = –3
–2p = –3 – 2
–2p = –5
2p = 5
p = 5/2
( –3 , q )
f ( x ) = –2x + 2
f ( –3 ) = –2x + 2 = q
–2 . –3 + 2 = q
6 + 2 = q
8 = q
q = 8
( r , 2 )
f ( x ) = –2x + 2
f ( r ) = –2x + 2 = 2
–2 . r + 2 = 2
–2r + 2 = 2
–2r = 2 – 2
–2r = 0
r = 0 : –2
r = 0
Jadi , nilai dari p , q , dan r adalah
p = 5/2 , q = 8 , r = 0 . ( C )