Diketahui f(x)=ax+b dengan f(4)=2 dan f(-1)=-8

f(4) = 2                                      f(-1) = -8                             4a + b = 2
f(4) = ax + b = 2                        f(-1) = ax + b = -8                -a + b = -8
      = a(4) + b = 2                             = a(-1) + b = -8             -------------    --
      =    4a + b =2                              =    -a + b = -8              5a + 0 = 10
                                                                                             -----         -----
                                                                                              5             5
                                                                                                      a = 2
                                                                                                
    4a + b = 2                        f(x) = ax =b
  4(2) + b = 2                        f(x) = 2x + (-6)     
        8 +b = 2
             b = 2-8
             b =-6