问题
解答题
计算:
(1)(a-3)(a+3)(a2+9);
(2)(2m+n)(2m-n)-(-m+2n)(-m-2n).
答案
(1)原式=(a2-9)(a2-9)
=(a2)2-92
=a4-81;
(2)原式=4m2-n2-(m2-4n2)
=4m2-n2-m2+4n2
=3m2+3n2.
计算:
(1)(a-3)(a+3)(a2+9);
(2)(2m+n)(2m-n)-(-m+2n)(-m-2n).
(1)原式=(a2-9)(a2-9)
=(a2)2-92
=a4-81;
(2)原式=4m2-n2-(m2-4n2)
=4m2-n2-m2+4n2
=3m2+3n2.