`1`
a)47,57.12,38+12,38.52,43
=12,38(47,57+52,43)
=12,38.100
=1238
b)155+2514−912+72+2511
`=\frac{1}{3}+(\frac{14}{25}+\frac{11}{25})-\frac{12}{9}+\frac{2}{7}`
`=1/3+1-4/3+2/7`
`=(1/3-4/3)+1+2/7`
`=-1+1+2/7`
`=0+2/7`
`=2/7`
`2`
`a)` `x-1/4=23/14`
`x=23/14-1/4`
`x=53/28`
`b)` `|2,5-x|=1,3`
`=>`[2,5−x=1,32,5−x=−1,3 `=>`[x=1,2x=3,8
`c)` `2^{225}=(2^3)^{75}=8^{75}`
`3^{150}=(3^2)^{75}=9^{75}`
Vì `8^{75}<9^{75}` nên 2225<3150.
