Jawabanmu

2013-12-17T19:48:34+07:00
A=20
b=17-20=-3
suku ke Un=a+(n-1)b
             50=20+49(-3)
                 =20-147=-127
1 3 1
2013-12-17T19:54:01+07:00
A = 20
b = U2-U1
  = 17 - 20
  = -3
Un = a + (n-1)b
U50 = 20 + (50-1)(-3)
       = 20 + 49(-3)
       = 20 - 147
       = - 127