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s(5) = 5, 0 = s(5)*s(6) + 15 = 5s(6) + 15 = 5[s(6) + 3], s(6) = -3.a(n) = a + (n-1)d.s(n) = na + n(n-1)d/2.a(6) = s(6) - s(5) = -3 - 5 = -8 = a + 5d,5 = s(5) = 5a + 5*4d/2 = 5a + 10d, 1 = a + 2d.-8 - 1 = (a+5d) - (a+2d) = 3d = -9, d = -3.a= a(1)=1 - 2d = 1 + 2*3 = 7.s(5) = 5a + 10d,s(6) = 6a + 15d,... |
