题目内容

简便计算及解方程
222×999+333×334 45×99 3(x+2)÷5=(x+2)
3(x+1)÷(2x-4)=6 7×( x-2 )=2x+3
2x-1
2
-
2x+5
3
=
10x-17
4
+1
分析:(1)根据乘法分配律进行计算;
(2)根据乘法分配律进行计算
(3)等式的两边同时乘上5,然后再进一步解答即可;
(4)等式的两边同时乘上(2x-4),然后再进一步解答即可;
(5)先计算7×( x-2 )=7x-14,然后再进一步解答即可;
(6)等式的两边同时乘上12,然后再进一步解答即可.
解答:解:(1)222×999+333×334,
=222×(333×3)+333×334,
=666×333+333×334,
=(666+334)×333,
=1000×333,
=333000;

(2)45×99,
=45×(100-1),
=45×100-45×1,
=4500-45,
=4455;

(3)3(x+2)÷5=(x+2),
   3(x+2)÷5×5=(x+2)×5,
         3(x+2)=(x+2)×5,
3(x+2)-3(x+2)=(x+2)×5-3(x+2),
         2(x+2)=0,
      2(x+2)÷2=0÷2,
              x+2=0,
            x+2-2=0-2,
                x=-2;

(4)3(x+1)÷(2x-4)=6,
3(x+1)÷(2x-4)×(2x-4)=6×(2x-4),
                    3(x+1)=6×(2x-4),
                        3x+3=12x-24,
                     3x+3-3x=12x-24-3x,
                       9x-24=3,
                    9x-24+24=3+24,
                          9x=27,
                       9x÷9=27÷9,
                           x=3;

(5)7×(x-2)=2x+3,
          7x-14=2x+3,
       7x-14-2x=2x+3-2x,
          5x-14=3,
       5x-14+14=3+14,
             5x=17,
          5x÷5=17÷5,
              x=3.4;

(6)
2x-1
2
-
2x+5
3
=
10x-17
4
+1

(
2x-1
2
-
2x+5
3
)×12=(
10x-17
4
+1)×12

   6(2x-1)-4(2x+5)=3(10x-17)+12,
           12x-6-8x-20=30x-51+12,
                 4x-26=30x-39,
              4x-26+39=30x-39+39,
                 4x+13=30x,
              4x+13-4x=30x-4x,
                   26x=13,
               26x÷26=13÷26,
                     x=0.5.
点评:四则运算,先弄清运算顺序,然后再进一步计算,能简算的要简算,要根据等式的性质进行解方程.
练习册系列答案
相关题目

违法和不良信息举报电话:027-86699610 举报邮箱:58377363@163.com

精英家教网