Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
1: \(x=\dfrac{3}{4}-\dfrac{2}{4}=\dfrac{1}{4}\)
2: \(x=\dfrac{2}{11}+\dfrac{1}{5}=\dfrac{10+11}{55}=\dfrac{21}{55}\)
Số tiền Nam mua sách: \(320000\times\dfrac{1}{4}=80000\) (đồng)
Số tiền Nam mua vở: \(90000:\dfrac{2}{3}=135000\) (đồng)
Số tiền Nam mua dụng cụ học tập: \(320000-\left(80000+135000\right)=105000\) (đồng)
\(9,MSC:195\\ \dfrac{9}{13}=\dfrac{9.15}{13.15}=\dfrac{135}{195}\\ \dfrac{-6}{65}=\dfrac{\left(-6\right).3}{65.3}=\dfrac{-18}{195}\\ \dfrac{-7}{39}=\dfrac{\left(-7\right).5}{39.5}=\dfrac{-35}{195}\\ 10,MSC:41154\\ \dfrac{12}{-57}=\dfrac{\left(-12\right).722}{57.722}=\dfrac{-8664}{41154}=\dfrac{-4}{19}\\ \dfrac{9}{38}=\dfrac{9.1083}{38.1083}=\dfrac{9747}{41154}=\dfrac{9}{38}\\ \dfrac{8}{19}=\dfrac{8.2166}{19.2166}=\dfrac{17328}{41154}=\dfrac{8}{19}\)
`B=(2015+2016+2017)/(2016+2017+2018)`
`=2015/(2016+2017+2018)+2016/(2016+2017+2018)+2017/(2016+2017+2018)`
Vì `2015/(2016+2017+2018)<2015/2016`
`2016/(2016+2017+2018)<2016/2017`
`2017/(2016+2017+2018)<2017/2018`
`=>B<A`
Bài 5
B= \(\dfrac{2015}{2016+2017+2018}\)+\(\dfrac{2016}{2016+2017+2018}\)+\(\dfrac{2017}{2016+2017+2018}\)
Ta có:\(\dfrac{2015}{2016}\)>\(\dfrac{2015}{2016+2017+2018}\),\(\dfrac{2016}{2017}\)>\(\dfrac{2016}{2016+2017+2018}\),\(\dfrac{2017}{2018}\)>\(\dfrac{2017}{2016+2017+2018}\)
⇒A>B
`1a)-17/30-11/(-15)+(-14)/24`
`=-17/30+22/30+(-7)/12`
`=5/30+(-7)/12`
`=1/6-7/12=2/12-7/12=-5/12`
`1b)(-10)/11*4/7+(-10)/11*3/7+1 10/11`
`=(-10)/11*(4/7+3/7)+1+10/11`
`=-10/11+10/11+1=1`
`1c)(5/7*0,6-5:3 1/2).(40%-1,4).(-2)^3`
`=(5/7*3/5-5:7/2).(0,4-1,4).(-8)`
`=(3/7-10/7).(-1).(-8)`
`=8.(-1)=-8`
c) \(\left(\dfrac{1}{2}\cdot x+\dfrac{1}{4}\right)\cdot\left(2x-\dfrac{1}{3}\right)=0\)
\(\dfrac{1}{2}\cdot x+\dfrac{1}{4}=0\)
\(\dfrac{1}{2}\cdot x=0-\dfrac{1}{4}\)
\(\dfrac{1}{2}\cdot x=-\dfrac{1}{4}\)
\(x=-\dfrac{1}{4}\div\dfrac{1}{2}\)
\(x=-\dfrac{1}{2}\)
\(2x-\dfrac{1}{3}=0\)
\(2x=0+\dfrac{1}{3}\)
\(2x=\dfrac{1}{3}\)
\(x=\dfrac{1}{3}\div2\)
\(x=\dfrac{1}{6}\)
\(\Rightarrow\) \(x=\) {\(-\dfrac{1}{2};\dfrac{1}{6}\)}