Jika diketahui f (x) =ax + b, f (1) =7 dan f (-3) =-1, maka nilai dari 2a-b adalah...

f(x) = ax + b

substitusi
f(1) = 1a + b = 7
f(-3)= -3a + b = -1
__________ -
= 4a + 0 = 8
= a = 8/4 = 2

dimasukkan
f(1) = 1a + b = 7
= 1(2) + b = 7
= 2 + b = 7
= b = 7-2
= b = 5

a= 2 b=5
Jadi,
2a- b = 2(2) - 5 = -1