解:(1)4x+3×0.7=6.5,
4x+2.1=6.5,
4x+2.1-2.1=6.5-2.1,
4x=4.4,
4x÷4=4.4÷4,
x=1.1;
(2)4x-1.6x=36,
(4-1.6)x=36,
2.4x=36,
2.4x÷2.4=36÷2.4,
x=15;
(3)
:
=x:10,
x=
×10,
x×8=
×10×8,
x=20.
分析:(1)原式變?yōu)?x+2.1=6.5,根據(jù)等式的性質(zhì),兩邊同減去2.1,再同除以4即可;
(2)根據(jù)乘法分配律改寫成(4-1.6)x=36,即2.4x=36,再根據(jù)等式的性質(zhì),兩邊同除以2.4即可;
(3)先根據(jù)比例的性質(zhì)改寫成
x=
×10,再根據(jù)等式的性質(zhì),兩邊同乘8即可.
點評:在解方程時應根據(jù)等式的性質(zhì),即等式兩邊同加上、同減去或同除以、同乘上某一個數(shù)(0除外),等式的兩邊仍相等,同時注意“=”上下要對齊.