Jawabanmu

2014-02-08T08:26:37+07:00
U5= 55
U8=148
a=?
U12=?

jawab
Un = a+(n-1)b

U5 = a+4b = 55
U8 = a+7b = 148 _ (dikurang)
     =    -3b = -93
              b = 31


U5 = a+4.31= 55
        a+124 =55
        a = 55-124
        a = -69

U12 = a+11b
       = -69 + 11.31
       = 272
       
2014-02-08T10:53:07+07:00
U₅ =a+(5-1)b=55
U₈ =a+(8-1)b=148
     = -3b=-93
     = b=31

U₅ =a+(4)31=55
   =a+124 =55
   =a =55-124
   =a = -69

U₁₂= -69+11.31
   = -69+341
   =272