\(\left|2x-1\right|+1=4\)

\(\left|2x-1\right|=4-1\)

\(\left|2x-1\right|=3\)

\(2x-1=3\) hoặc \(2x-1=-3\)

\(2x=3+1\)          \(2x=\left(-3\right)+1\)

\(2x=4\)                \(2x=-2\)

\(x=4\div2\)            x = (-2) \(\div\) 2

x = 2                   x =  -1 

Áp dụng tính chất của dãy tỉ số bằng nhau:

\(\dfrac{x}{4}=\dfrac{y}{7}=\dfrac{x-2y}{4-14}=\dfrac{90}{-10}=-9\)

\(\dfrac{x}{4}=-9\Rightarrow x=4.\left(-9\right)=-36\)

\(\dfrac{y}{7}=-9\Rightarrow y=7.\left(-9\right)=-63\)

Vậy \(x=-36;y=-63\) 

a) \(\sqrt{49}+\sqrt{4}=7+2=9\)

b) \(\sqrt{0,25}-\sqrt{0,01}=0,5-0,1=0,4\)

c) \(\sqrt{\dfrac{16}{25}}-\sqrt{\dfrac{1}{81}}=\dfrac{4}{5}-\dfrac{1}{9}=\dfrac{31}{45}\)

d) \(\sqrt{64}-\sqrt{16}+\sqrt{\left(-3\right)^2}=8-4+3=4+3=7\)

e) \(2-\sqrt{0,36}=2-\dfrac{3}{5}=\dfrac{10}{5}-\dfrac{3}{5}=\dfrac{7}{5}\)

a) \(\sqrt{20}\) + \(\sqrt{45}\) - \(\sqrt{5}\)

= 2\(\sqrt{5}\) + \(3\sqrt{5}\) - \(\sqrt{5}\)

= \(4\sqrt{5}\)

b) \(\sqrt{121}\) + \(\sqrt{81}\) - \(\sqrt{16}\)

= 11 + 9 - 4

= 20 - 4

= 16

Câu khẳng định: This dress was beautiful.

Câu phủ định: This dress wasn't / was not beautiful.

Câu nghi vấn: Was this dress beautiful?

All are correct

2. A. important

7. C. to keep

11. B. forgets

  My school is not very big, so there is not enough space for all the students to play in break time. We do not have permission to go out, so everything in break time is limited in the school yard. Most of us choose to sit in our classes to play some small games or try to study for the next lesson. Some others go to the library to read books, and they also try to rest for a few minutes in that quiet place. If we feel hungry, we can go to the canteen to buy some food. Our canteen has almost all of the things that young people love to eat, so that is the most crowded place in break time. Some students who come early to the yard have some space to play badminton or basketball. The losers will get out of the playground to give the turn to other students outside. Although there are only 15 minutes of break, students like us really value it.