Jawabanmu

2014-05-05T18:57:47+07:00
U4 = 19 U7 = 37 a + 3b = 19 a + 6b = 37 _________________ - -3b = -18 b = 6 a + 3b = 19 a + 3.6 = 19 a = 19-18 a = 1 Sn = 1/2 * n ( 2a + (n-1)b) S24 = 1/2 * 24 ( 2 + 23 * 6) S24 = 12 * 140 S24 = 1680