(a+1)(a2+1),第二个括号内是a的平方a3+a2+a+1=a2(a+1)+a+1=(a+1)(a2+1)
a"’ + a” + a + 1= a”( a + 1 ) + ( a + 1 )= ( a + 1 )( a” + 1 )= ( a + 1 )[ a” - (-1) ]= ( a + 1 )[ a” - ( i )” ]= ( a + 1 )( a - i )( a + i )
提取公因数,结果等于(a的平方+1)(a+1)
a2(a+1)2