Question

Diketahui rumus fungsi f(x) = ax+b. jika f(1)=4 dan f(2)=9. nilai f(-2) Adalah...

Answer 1

F(x)= ax+b

f(1)=a.1+b=4
f(2)=a.2+b=9

1.a+b=4 (x) 2 => 2a+2b=8
2.a+b=9 (x) 1 => 2a+b=9
                               b=-1

1.a+b=4
1.a+(-1)=4
a=4+1
a=5

f(x)=ax+b
f(-2)=ax+b
      = 5.(-2) +(-1)
      = -10 + -1
      =-11

Answer 2

F(1) = 4
a + b = 4.......(pers1)
f(2) = 9
2a + b = 9.......(pers2)
eliminasi pers 1 dan pers 2
a + b = 4
2a+b = 9

-a = - 5
a = 5
sekarang cari nilai b
a + b = 4
5 + b = 4
b = -1
maka nilai f(-2) :
-2a + b = -2(5) + (-1)
           = -11