递等式计算下面各题.72-44+85 234-135÷9 144+(57-12)×2 95-15×6+41 (15+20
1个回答

解题思路:(1)按照从左到右的顺序计算;

(2)先算除法,再算减法;

(3)先算减法,再算乘法,最后算加法;

(4)先算乘法,再算减法,最后算加法;

(5)先算小括号里面的加法,再算括号外的乘法;

(6)先同时运算两个小括号里面的加法和减法,再算除法.

(1)72-44+85,

=28+85,

=113;

(2)234-135÷9,

=234-15,

=219;

(3)144+(57-12)×2,

=144+45×2,

=144+90,

=234;

(4)95-15×6+41,

=95-90+41,

=5+41,

=46;

(5)(15+20)×3,

=35×3,

=105;

(6)(75+30)÷(20-5),

=105÷15,

=7.

点评:

本题考点: 整数四则混合运算.

考点点评: 本题关键是理清楚运算的顺序,找出先算什么,再算什么,根据运算的顺序逐步求解即可.