用递等式计算.
(1)8.7×63+63×1.3???????????????????????????? (2)3.6÷[(1.2+0.4)×5]
(3)1.2+8.8×1.25??????????????????????????????? (4)1.2×8.8×1.25
(5)(2.5÷2+2÷2.5)×0.4???????????????????????(6)(5.7×1.2+4.3×1.2)×2.5.
网友回答
解:(1)8.7×63+63×1.3,
=(8.7+1.3)×63,
=10×63,
=630;
(2)3.6÷[(1.2+0.4)×5],
=3.6÷[1.6×5],
=3.6÷8,
=0.45;
(3)1.2+8.8×1.25,
=1.2+(8+0.8)×1.25,
=1.2+(8×1.25+0.8×1.25),
=1.2+(10+1),
=1.2+11,
=12.2;
(4)1.2×8.8×1.25,
=1.2×(8.8×1.25),
=1.2×11,
=13.2;
(5)(2.5÷2+2÷2.5)×0.4,
=(1.25+0.8)×0.4,
=1.25×0.4+0.8×0.4,
=0.5+0.32,
=0.82;
(6)(5.7×1.2+4.3×1.2)×2.5,
=(5.7+4.3)×1.2×2.5,
=10×1.2×2.5,
=12×2.5,
=30.
解析分析:(1)根据乘法分配律进行简算;(2)先算小括号里面的加法,再算中括号里面的乘法,最后算除法;(3)把8.8拆成8+0.8,然后再根据乘法分配律进行简算;(4)根据乘法结合律进行简算即可;(5)先算小括号里面的除法,再根据乘法分配律进行简算;(6)根据乘法分配律进行简算即可.
点评:四则运算,先弄清运算顺序,然后再进一步计算即可,能简算的要简算.