tokeman
幼苗
共回答了18个问题采纳率:94.4% 举报
15² = (10 × 1 + 5)² = 100 × 1 × (1 + 1)+ 25 = 225
25² = (10 × 2 + 5)² = 100 × 2 × (2 + 1)+ 25 = 625
35² = (10 × 3 + 5)² = 100 × 3 × (3 + 1)+ 25 = 1225
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n5² = (10 × n + 5)² = 100 n (n + 1)+ 25 = 100 n² + 100 n + 25
1年前
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