Answers to the basic training of mathematics in the first day of junior high school

If you don't think from expression, you just get some ideas from perceptual thinking.

Look to the right.

8*3-8* 1=8*2; 8*6-8*3=8*3; 8* 10-8*6=8*4 and so on.

It is exactly eight times that of 65438 +0, 2, 3, etc.

On the left,

5 square -3 square = 2 * 8 = 2 * 4 * 2; 7 square -5 square = 2 *12 = 2 * 4 * 3; Square of 9-square of 7 =2* 16=2*4*4 and so on.

Just 2 times 2, 3, 4, etc.

This rule can be expressed as follows: the left side of the nth formula is 2*4*n more than the previous formula, and the right side is 8 * n； more;

Judging from the results, the proof is obvious. Of course, this law can be strictly proved by mathematical induction.