Jawabanmu

2014-03-16T14:21:46+07:00
A= 2k+25
b= (-k+9)-(2k+25)
  b= -3k-16

jadi U5=a+4b
     U5= (2k+25) + 4(-3k-16)
         = (2k+25) + (-12k-64)
        U5 = -10k-52
sorry salah baca soal

S5 = 5/2 (4k+50)+4(-3k-16)
=5
=5/2 (4k+50-12k-64)
=5/2 (-8k-14)
=hitung sndri..