用递等式计算,能简便的用简便方法计算:916-816÷48×8??????73×2.87+2.87×26+2.871.56÷0.24×(7-6.8)0.9×[0.8-

发布时间:2020-08-07 10:01:30

用递等式计算,能简便的用简便方法计算:
916-816÷48×8??????
73×2.87+2.87×26+2.87
1.56÷0.24×(7-6.8)
0.9×[0.8-(0.2÷0.5+0.3)]
当a=2.5、b=9、c=0.4时,求abc的值.

网友回答

解:(1)916-816÷48×8,
=916-17×8,
=916-136,
=780;

(2)73×2.87+2.87×26+2.87,
=(73+26)×2.87,
=100×2.87,
=287;

(3)1.56÷0.24×(7-6.8),
=6.5×0.2,
=1.3;

(4)0.9×[0.8-(0.2÷0.5+0.3)],
=0.9×[0.8-(0.4+0.3)],
=0.9×[0.8-0.7],
=0.9×0.1,
=0.09;

(5)abc=2.5×9×0.4,
=(2.5×0.4)×9,
=1×9
=9.
解析分析:(1)先算除法和乘法,再算减法;
(2)运用乘法分配律简算;
(3)先算括号内的,再算除法和乘法;
(4)先算小括号内的除法,再算小括号内的加法,然后算中括号内的减法,最后算括号外的乘法;
(5)把a、b、c的值代入abc中,运用乘法交换律与结合律计算即可.

点评:此题主要考查小数的四则混合运算的运算顺序,以及应用运算定律进行简便计算.
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