(1)计算:(a+3) 2 -a(4+a);(2)(8a 3 b-5a 2 b 2 )÷4ab;(3)先分解因式,再求值:5ab 2 -10

2025-06-21 12:29:04
推荐回答(1个)
回答1:

(1)(a+3) 2 -a(4+a),
=a 2 +6a+9-4a-a 2
=2a+9;

(2)(8a 3 b-5a 2 b 2 )÷4ab,
=8a 3 b÷4ab-5a 2 b 2 ÷4ab,
=2a 2 -
5
4
ab;

(3)5ab 2 -10ab+5a,
=5a(b 2 -2b)+5a,
=5a(b 2 -2b+1),
=5a(b-1) 2
当a=
1
3
,b=-
1
2
时,
原式=5×
1
3
×(-
1
2
-1) 2 =
15
4