\(1,2:\frac{3}{5}+\left(1\frac{1}{15}-\frac{8}{15}\right)x2\frac{2}{4}\)

\(=\frac{6}{5}x\frac{5}{3}+\left(\frac{16}{15}-\frac{8}{15}\right)x\frac{10}{4}\)

 \(=2+\frac{8}{15}x\frac{10}{4}=2+\frac{2}{3}\)

 \(=2\frac{2}{3}\)

\(1,2:\frac{3}{5}+\left(1\frac{1}{15}-\frac{8}{15}\right)\cdot2\frac{2}{4}\)

\(=\frac{6}{5}\cdot\frac{5}{3}+\left(\frac{16}{15}-\frac{8}{15}\right)\cdot\frac{10}{4}\)

\(=\frac{30}{15}+\frac{8}{15}\cdot\frac{10}{4}\)

\(=\frac{30}{15}+\frac{80}{60}=\frac{200}{60}\)

Bạn viết như này ai hiểu

Viết lại đề lại sách nháp đi

\(\Rightarrow\frac{\left(\frac{518}{19}-\frac{342}{13}\right).\left(\frac{253}{236}-\frac{3}{318}\right)}{\left(\frac{3}{4}+x\right)\frac{27}{33}}\)=\(\frac{\frac{1}{3}.\frac{3}{36}+\frac{1}{3}.\frac{3}{14.17}}{\frac{1}{2}.\frac{2}{13.15}+\frac{1}{2}.\frac{2}{14.16}}\)

\(\frac{\frac{236}{2247}.\frac{247}{236}}{\left(\frac{3}{4}+x\right)\frac{27}{33}}\)=\(\frac{\frac{1}{3}.\left(\frac{1}{13}-\frac{1}{16}+\frac{1}{14}-\frac{1}{17}\right)}{\frac{1}{2}\left(\frac{1}{13}+\frac{1}{14}-\frac{1}{16}-\frac{1}{17}\right)}\)

\(\frac{1}{\left(\frac{3}{4}+x\right)\frac{27}{33}}\)=\(\frac{\frac{1}{3}}{\frac{1}{2}}\)

đến đây tự làm nhé cứ ra 13/12 là được

A )  2/17 + 30/46 + 15/17 + 4/49 + 8/23=102/49

B ) 5/8 x ( 19/31 x 8/5 )=19/31

C ) 7/9 x 8/15 x 9/7 x 15/4=2

D ) 11/12 x 24/7 x 21/22=3

nhìu quá nên mk chỉ cho kết quả thôi nha ^-^!!!

Bài 1:

a) Ta có: \(B=\left(2x-5\right)\cdot3x-2x\left(3x+1\right)\)

\(=6x^2-15x-6x^2-2x\)

\(=-17x\)

Thay \(x=\frac{1}{2}\) vào biểu thức B=-17x, ta được:

\(B=-17\cdot\frac{1}{2}=\frac{-17}{2}\)

Vậy: \(-\frac{17}{2}\) là giá trị của biểu thức \(B=\left(2x-5\right)\cdot3x-2x\left(3x+1\right)\) tại \(x=\frac{1}{2}\)

b) Ta có: \(G=\left(x+3\right)\cdot4x-3x\left(x-2\right)-x^2\)

\(=4x^2+12x-3x^2+6x-x^2\)

=18x

Thay x=-2 vào biểu thức G=18x, ta được:

\(G=18\cdot\left(-2\right)=-36\)

Vậy: -36 là giá trị của biểu thức \(G=\left(x+3\right)\cdot4x-3x\left(x-2\right)-x^2\) tại x=-2

Bài 2:

Sửa đề: \(P=\left(x-2\right)\cdot x-3x\left(x+1\right)+2x^2+5x-3\)

Ta có: \(P=\left(x-2\right)\cdot x-3x\left(x+1\right)+2x^2+5x-3\)

\(=x^2-2x-3x^2-3x+2x^2+5x-3\)

\(=-3\)

Vậy: P không phụ thuộc vào x(đpcm)

1) ta có: \(x:3=y.15\Rightarrow x\cdot\frac{1}{3}=y.15\Rightarrow\frac{x}{15}=\frac{y}{\frac{1}{3}}\)

ADTCDTSBN

...

2) bn ghi thiếu đề r

3) ta có: \(3x=7y\Rightarrow\frac{x}{7}=\frac{y}{3}=k\Rightarrow\hept{\begin{cases}x=7k\\y=3k\end{cases}}\)

mà xy = 189 => 7k.3k = 189

                          21 k² = 189

                                 k² = 9 = 3² = (-3)² => k = 3 hoặc k  = - 3

TH1: k = 3

x = 7.3 => x  = 21

y = 3.3 => y = 9

...

4) ta có: \(4x=5y\Rightarrow\frac{x}{5}=\frac{y}{4}\Rightarrow\frac{x^2}{25}=\frac{y^2}{16}\)

ADTCDTSBN

...

uses crt;

begin

clrscr;

writeln((5-2*3)/2:4:2);

writeln((15*4-8)*3);

writeln((15 div 2) mod 3);

writeln((245 div 10) div 3) mod 2);

readln;

end.

Tham khảo đoạn này nhé

The Covid 19 translation is currently raging across the country. It has claimed many lives and pain of the people. So in the country we have opened the door to online learning for the better. I find that online learning gives me many opportunities that I have never seen before in major lectures, and learning online still helps me acquire the same quantitative knowledge as studying in school. Firstly, online learning helps me to grasp the lecture better, because the teacher will speak or record the Lecture via microphone and when listening to the lecture, the audio will be very clear and easy to hear. This is much more beneficial for listening to my sermons because the sermons are large and broad,. Secondly, in online lessons, besides the call called Zoom, teachers often record the lecture and post it on the school's intranet, so I can easily review the lecture anytime, anywhere. Furthermore I have: A comfortable study space. Flexible study time. Easy to store study materials. Although that is the case, there are a number of friends who have played and skipped school thanks to learning Zoom. That is really spoiled. We should advise you to study better. Protecting our planet is protecting ourselves

tham khảo nha:

One of the benefits of online learning is convenience. Instead of having to study at one location, learning and teaching can be done at home. Teachers and students can study on a tablet or laptop so learning can take place almost anywhere without having to worry that the classroom is too far from home. Online learning also saves time for teachers, students and parents. No more travel, shuttle or worry about the distance to class, and that time can be spent on other activities. While in the classroom, some students could not clearly see the writing on the blackboard when the teacher was giving the lecture. This also affects the student's ability to concentrate and absorb. The difference of online learning is that they allow participants to share their screens during the lecture. This is more convenient for lectures because everyone can clearly see the content, increase the ability to focus and absorb the students.

a) Ta có: \(-3\dfrac{1}{4}\cdot x-75\%+\dfrac{3x}{2}=-1.2:\dfrac{-9}{10}-1\dfrac{1}{4}\)

\(\Leftrightarrow\dfrac{-13x}{4}-\dfrac{3}{4}+\dfrac{3x}{2}=\dfrac{-6}{5}\cdot\dfrac{10}{-9}-\dfrac{5}{4}\)

\(\Leftrightarrow\dfrac{-13x-3+6x}{4}=\dfrac{4}{3}-\dfrac{5}{4}\)

\(\Leftrightarrow\dfrac{-7x-3}{4}=\dfrac{1}{12}\)

\(\Leftrightarrow-7x-3=\dfrac{1}{3}\)

\(\Leftrightarrow-7x=\dfrac{10}{3}\)

hay \(x=-\dfrac{10}{21}\)

b) Ta có: \(\dfrac{5}{3}+\dfrac{5}{15}+\dfrac{5}{35}+...+\dfrac{5}{x\left(x+2\right)}=2\dfrac{8}{17}\)

\(\Leftrightarrow\dfrac{5}{2}\left(\dfrac{2}{3}+\dfrac{2}{15}+\dfrac{2}{35}+...+\dfrac{2}{x\left(x+2\right)}\right)=2\dfrac{8}{17}\)

\(\Leftrightarrow\dfrac{5}{2}\left(1-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{5}+...+\dfrac{1}{x}-\dfrac{1}{x+2}\right)=2+\dfrac{8}{17}\)

\(\Leftrightarrow\left(1-\dfrac{1}{x+2}\right)=\dfrac{42}{17}:\dfrac{5}{2}\)

\(\Leftrightarrow\dfrac{x+1}{x+2}=\dfrac{42}{17}\cdot\dfrac{2}{5}=\dfrac{84}{85}\)

\(\Leftrightarrow85x+85=84x+168\)

\(\Leftrightarrow x=83\)