来自韩永的问题
(1)计算:(a+3)2-a(4+a);(2)(8a3b-5a2b2)÷4ab;(3)先分解因式,再求值:5ab2-10ab+5a,其中a=13,b=−12.
(1)计算:(a+3)2-a(4+a);
(2)(8a3b-5a2b2)÷4ab;
(3)先分解因式,再求值:5ab2-10ab+5a,其中a=13,b=−12.


(1)计算:(a+3)2-a(4+a);(2)(8a3b-5a2b2)÷4ab;(3)先分解因式,再求值:5ab2-10ab+5a,其中a=13,b=−12.
(1)计算:(a+3)2-a(4+a);
(2)(8a3b-5a2b2)÷4ab;
(3)先分解因式,再求值:5ab2-10ab+5a,其中a=13,b=−12.
(1)(a+3)2-a(4+a),
=a2+6a+9-4a-a2,
=2a+9;
(2)(8a3b-5a2b2)÷4ab,
=8a3b÷4ab-5a2b2÷4ab,
=2a2-54