If you look at the following formulas, what rules do you find? 3 × 5 = 15, and 15 = 42-1; 5 × 7 = 35, and 35 = 62-1,11 If you look at the following formulas, what rules will you find? 3 × 5 = 15, and 15 = 42-1; 5 × 7 = 35, and 35 = 62-1, 11 × 13 = 143, and 143 = 122-1____________ .

If you look at the following formulas, what rules do you find? 3 × 5 = 15, and 15 = 42-1; 5 × 7 = 35, and 35 = 62-1,11 If you look at the following formulas, what rules will you find? 3 × 5 = 15, and 15 = 42-1; 5 × 7 = 35, and 35 = 62-1, 11 × 13 = 143, and 143 = 122-1____________ .

(x-1)(x+1)=x²-1