12345*12346-12344*12343简便运算

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12345*12346-12344*12343简便运算
12345*12346-12344*12343
简便运算

12345*12346-12344*12343简便运算
12345*12346-12344*12343
=12345×(12345+1)-(12343+1)×12343
=12345的平方+12345-12343的平方-12343
=12345的平方-12343的平方+2
=(12345+12343)×(12345-12343)+2
=24688×2+2
=49376+2
=49378

49378

49378

设x=12343
原式=(n+2)(n+3)-n(n+1)
=n^2+5n+6-n^2-n
=4n+6
=4*12343+6
=49378

49378