4×（2P＋3q）²一（3p一q）²
=[2(2P＋3q)] ²一（3p一q）²
=(4p+6q) ²一（3p一q）²
=(4P+6q一3p+q)( 4P+6q+3p一q)
=(p+7q)(7p+5q)