 reserve n,s for Nat;

theorem Th86:
  SumsReciTriang = seq_const 2 + - geo-seq (2,1)
  proof
    for k being Nat holds
      SumsReciTriang.k = (seq_const 2).k + (- geo-seq (2,1)).k
    proof
      let k be Nat;
A1:   SumsReciTriang.k = 2 - 2 / (k + 1) by Def14;
A2:   (seq_const 2).k = 2 by SEQ_1:57;
      - (geo-seq(2,1)).k = (- geo-seq(2,1)).k by VALUED_1:8; then
      (- geo-seq(2,1)).k = - 2 / (k + 1) by Def15;
      hence thesis by A1,A2;
    end;
    hence thesis by SEQ_1:7;
  end;
