Original formula = (2bc) 2-(b 2+c 2-a 2) 2

= [2bc+(B2+C2-A2)] * [2bc-(B2+C2-A2)] (square difference formula)

= [2bc+B2+C2-A2] * [2bc-B2-C2+A2)] (without brackets)

= [(2bc+B2+C2)-A2] * [A2-(B2+C2-2bc)] (brackets, square term of purpose)

= [(b+c) 2-a 2] * [a 2-(b-c) 2] (complete square formula)

=(b+c+a)(b+c-a)(a+b-c)(a-b+c) (square difference formula)

Btw: Now, according to the new curriculum standard, the content of factorization has been reduced in the middle school entrance examination questions all over the country, and there will be no more complicated calculations.