解方程.
(1)7x+4-46
(2)9x-15=57
(3)96+12x=144
(4)3.2x-9.8=9.4
(5)x+4.6×3=16.9
(6)7×5-5x=33.5
(7)x-0.64=36
(8)4(2x一0.8x)=16.8
(9)3.6x+2.4x-3.6=0.
解:(1)7x+4=46,
7x+4-4=46-4,
7x÷7=42÷7,
x=6;
(2)9x-15=57,
9x-15+15=57+15,
9x÷9=72÷9,
x=8;
(3)96+12x=144,
96+12x-96=144-96,
12x÷12=48÷12,
x=4;
(4)3.2x-9.8=9.4,
3.2x-9.8+9.8=9.4+9.8,
3.2x÷3.2=19.2÷3.2,
x=6;
(5)x+4.6×3=16.9,
x+13.8=16.9.
x+13.8-13.8=16.9-13.8,
x=3.1;
(6)7×5-5x=33.5,
35-5x+5x=33.5+5x,
35-33.5=33.5+5x-33.5,
1.5÷5=5x÷5,
x=0.3;
(7)x-0.64=36,
x-0.64+0.64=36+0.64,
x=36.64;
(8)4(2x-0.8x)=16.8,
4.8x=16.8,
4.8x÷4.8=16.8÷4.8,
x=3.5;
(9)3.6x+2.4x-3.6=0,
6x-3.6=0+3.6,
6x÷6=3.6÷6,
x=0.6.
分析:(1)依據(jù)等式的性質(zhì),方程兩邊同時(shí)減4,再同時(shí)除以7求解,
(2)依據(jù)等式的性質(zhì),方程兩邊同時(shí)加15,再同時(shí)除以9求解,
(3)依據(jù)等式的性質(zhì),方程兩邊同時(shí)減96,再同時(shí)除以12求解,
(4)依據(jù)等式的性質(zhì),方程兩邊同時(shí)加9.8,再同時(shí)除以3.2求解,
(5)先化簡(jiǎn)方程,再依據(jù)等式的性質(zhì),方程兩邊同時(shí)減13.8求解,
(6)先化簡(jiǎn)方程,再依據(jù)等式的性質(zhì),方程兩邊同時(shí)加5x,再同時(shí)減33.5,最后同時(shí)除以5求解,
(7)依據(jù)等式的性質(zhì),方程兩邊同時(shí)加0.64求解,
(8)先化簡(jiǎn)方程,再依據(jù)等式的性質(zhì),方程兩邊同時(shí)除以4.8求解,
(9)先化簡(jiǎn)方程,再依據(jù)等式的性質(zhì),分成兩邊同時(shí)加3.6,最后同時(shí)除以6求解.
點(diǎn)評(píng):(1)方程能化簡(jiǎn)先化簡(jiǎn),(2)等號(hào)要對(duì)齊,是解方程要注意的地方.