求未知数x.10x=2.50.86×3-1.8x=7.2x-18x=9.45.-数学

题目简介

求未知数x.10x=2.50.86×3-1.8x=7.2x-18x=9.45.-数学

题目详情

求未知数x.
10
x
=
2.5
0.8

6×3-1.8x=7.2         
x-
1
8
x=9.45.
题型:解答题难度:中档来源:不详

答案

(1)class="stub"10
x
=class="stub"2.5
0.8

       2.5x=10×0.8,
  2.5x÷2.5=8÷2.5,
          x=3.2;

(2)6×3-1.8x=7.2,
       18-1.8x=7.2,
  18-1.8x+1.8x=7.2+1.8x,
            18=7.2+1.8x,
        18-7.2=7.2+1.8x-7.2,
          10.8=1.8x,
     10.8÷1.8=1.8x÷1.8,
             x=6;

(3)x-class="stub"1
8
x=9.45,
       class="stub"7
8
x=9.45,
    class="stub"7
8
class="stub"7
8
=9.45÷class="stub"7
8

         x=10.8.

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