用等式性质解方程(1)
1:
⑴ B ⑵ A ⑶ A ⑷ B
2:
x+43=101 x-17=45 8.5+x=10.2 x-0.74=1.5
x=101-43 x=45+17 x=10.2-8.5 x=0.74+1.5
x=58 x=62 x=1.7 x=2.24
3:
⑴题根据数量关系“红彩带的长+2.7=蓝彩带的长”,
可列方程
x+2.7=6.9,
x+2.7-2.7=6.9-2.7
x=4.2
⑵题根据数量关系“红彩带的长+x=蓝彩带的长”,
可列方程
x+4.2=6.9
x=6.9-4.2
x=2.7