| 317×99+317 | 12-5x=6.5 |
| (2.28+1.8)×6.5 | 19÷[( + )÷ ]. |
=(99+1)×317,
=100×317,
=31700;
(2)12-5x=6.5,
12-5x+5x=6.5+5x,
12-6.5=6.5+5x-6.5,
5.5=5x,
5.5÷5=5x÷5,
x=1.1;
(3)(2.28+1.8)×6.5,
=4.08×6.5,
=4×6.5+0.08×6.5,
=26+0.52,
=26.52;
(4)19÷[(
+
)÷
],=19÷[
],=19
,=10.
分析:(1)(3)运用乘法分配律解答,
(2)依据等式的性质,方程两边同时加5x,再同时减6.5,最后同时除以5求解,
(4)按照先算小括号里面的,再算中括号里面的,最后算除法的顺序解答.
点评:本题考查知识点:(1)四则运算计算顺序,(2)依据等式的性质解方程,(3)简便算法运用.