Jawabanmu

2014-04-16T15:45:45+07:00
U2 = a + b   = 46         U25 = a+24b=50+24(-4)=-46
U5 = a + 4b = 34
             -3b = 12
                 b = -4
a + b = 46
a - 4 = 46
a = 50
S25 = 25/2 ( 50 + (-46) = 50
2014-04-16T15:49:17+07:00
A + 1b = 46
a + 4b = 34
----------------- -
     -3b = 12
        b = 12/-3
        b = -4
a + 1.-4 = 46
        a  = 50

S25 = 25/2 (2.50 + 24.-4)
       = 12,5 (100 + (-96))
       = 12,5 (4)
       = 50

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