Observe the following equations: 4-1 = 3, 9-4 = 5, 16-9 = 7, 25-16 = 9, 36-25 = 11 Let n be a natural number, and let n be an equation containing n______ .

Observe the following equations: 4-1 = 3, 9-4 = 5, 16-9 = 7, 25-16 = 9, 36-25 = 11 Let n be a natural number, and let n be an equation containing n______ .

The equation is sorted out: 22-12 = 1 × 2 + 1; 32-22 = 2 × 2 + 1; 42-32 = 2 × 3 + 1 So the rule is: (n + 1) 2-n2 = 2n + 1; so the answer is: (n + 1) 2-n2 = 2n + 1