求未知数χ. (1)χ-
(2)5χ-2.5×4=0.5 (3)
|
(1)x-
x=1 3
,3 10
x=2 3
,3 10
x÷2 3
=2 3
÷3 10
,2 3
x=
×3 10
,3 2
x=
;9 20
(2)5x-2.5×4=0.5,
5x-10=0.5,
5x-10+10=0.5+10,
5x=10.5,
5x÷5=10.5÷5,
x=2.1;
(3)
:x=1 6
:3 10
,3 5
x=3 10
×1 6
,3 5
x÷3 10
=3 10
÷1 10
,3 10
x=
.1 3