Question

F (x) = px + q
f (1) = 5
f (3) = 11
berapa f (-1) + (4)...

Answer 1

Masukin dulu nilai f1 dan f2 ke rumus:
1. f(1)= p(1)+q= 5    /*3 ...3p+3q= 15
2. f(3)= p(3)+q= 11  /*1 ...3p+ q=  11
dikurangi, ketemu 2q=4, berarti q=2
selanjutnya, masukin nilai q ke x1 rumus, misal p+q=5, berarti p+2=5. Ketemu p=5-2=3
Selanjutnya masukin ke rumus f(-1) + f(4)
Jadi [3(-1)+2]+[3(4)+2]=-1+14=13
Klo ga salah lho ya...

Answer 2

F(x)=px + q

f (-1) = 1 ->    p + q = 5    
f ( 3 ) = 11 -> 3p + q = 11

p + q = 5
3p + q = 11 ( eliminasi q )

= -2p = -6
     p = 3

p + q = 5
q = 5 - 3 = 2

jd fungsinya f(x) = 3x + 2

f(-1) + f(4) = 3(-1) + 2 + ( 3(4) + 2 )
               = 13