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

Thay x=-1/3;y=3 vào A, ta được:

\(A=\left[3\cdot\dfrac{-1}{3}+1\right]^3-\left(3-2\right)^2+\left(3-1\right)^3+\left(-\dfrac{1}{3}+3\right)^2\)

\(=-1^2+2^3+\left(\dfrac{8}{3}\right)^2\)

\(=\dfrac{64}{9}+7=\dfrac{127}{9}\)

\(A=\left(3x+1\right).3-\left(y-2\right).2+\left(y-1\right).3+\left(x+y\right).2\\ \Leftrightarrow A=3.\left(3x+1+y-1\right)+2.\left(x+y-y+2\right)\\ \Leftrightarrow A=3.\left(3x+y\right)+2.\left(x+2\right)\)
Thay \(x=-\dfrac{1}{3};y=-3\) được:
\(A=3.\left[3.\left(-\dfrac{1}{3}\right)+\left(-3\right)\right]+2.\left[\left(-\dfrac{1}{3}\right)+2\right]\\ \Leftrightarrow A=3.\left(-1-3\right)+2.\dfrac{5}{3}\\ \Leftrightarrow A=3.\left(-4\right)+2.\dfrac{5}{3}\\ \Leftrightarrow A=-12+\dfrac{10}{3}\\ \Leftrightarrow A=-\dfrac{26}{3}\)
Vậy \(A=-\dfrac{26}{3}\) tại \(x=-\dfrac{1}{3};y=-3\)

1) He likes dancing and I do, too. (hobby)

=> He has the same hobby as I do.

2) Today isn't as hot as yesterday.

=> Yesterday  _it was hotter than today________________________

3) I am as old as my cousin.

=> I am the __same age as my cousin_______________________

4) He is the smartest student in my class.

=> No one __in my class is as smart as him______________________

5) My house is green and your house is green, too.

=> My house is _____the same colour as mine____________________

6) The snake is as long as the ruler.

=> The snake ___is the same length as the ruler______________________

7) No one in my family is as heavy as my father.

=> My father is __the heaviest in my family_______________________

I have never eaten a more delicious cake than this before.

=> This is the ____most delicious cake I have ever eaten_____________________

9) Playing video games is not as good as exercising. (better)

=> Exercising ____is better than playing video games_____________________

10) David is more astistic than Nick. (not)

=> Nick ___is not as artistic as David______________________

\(\left(-\dfrac{3}{5}\right)^2.\dfrac{5}{11}+\dfrac{9}{25}.\left(-\dfrac{16}{11}\right)\)

\(=\dfrac{9}{25}.\dfrac{5}{11}+\dfrac{9}{25}.\left(-\dfrac{16}{11}\right)\)

\(=\dfrac{9}{25}.\left[\dfrac{5}{11}+\left(-\dfrac{16}{11}\right)\right]\)

\(=\dfrac{9}{25}.\left(-1\right)\)

\(=-\dfrac{9}{25}\)

Số kg sắt quặng A :

\(80x\dfrac{40}{100}=32\left(kg\right)\)

Tổng số kg sắt quặng B :

\(32+20=52\left(kg\right)\)

Tổng số kg quặng B gồm cả sắt :

\(80+20=100\left(kg\right)\)

Phần trăm sắt quặng B :

\(\dfrac{52}{100}x100\%=52\%\)

Đáp số : \(52\%\)

Quặng B nặng số kg là: 

`80 + 20= 100 (kg)`

Nung `80`kg quặng A thu được số kg sắt là: 

`80 : 100` x `40 = 32 (kg)`

Số kg sắt có trong quặng B là: 

`32+ 20 = 52 (kg)`

Quặng B chứa % sắt là: 

`52 : 100 `  x `100 = 52`% (sắt)

Đáp số: ....

em mới năm nay lên lớp 6 thôi nhưng vì em học tiếng anh sớm nên em có làm được một đoạn văn tiếng anh giống với đề bài,một số từ ngữ em không biết nên dùng sách tham khảo ạ:School days in the past for fifth graders were a mix of routine and fun. Classes started early, around 8 a.m., with subjects like math, reading, and science. Students used chalk and blackboards, and textbooks were often well-worn. During breaks, kids played outside, enjoying games like tag or jump rope. Summer holidays were a highlight, offering endless days for playing with friends, exploring nature, or visiting family. Getting to school might mean walking, biking, or taking a horse-drawn carriage. These simpler times were filled with laughter, learning, and the excitement of childhood adventures.

oh bạn học cả t anhh lớp 9 trc aF

7\(x\).2 hay 7\(x^2\) vậy em?

7x^2 ạ

\(a.\dfrac{-3}{7}\cdot\dfrac{15}{13}-\dfrac{3}{7}\cdot\dfrac{11}{13}-\dfrac{3}{7}\\ =-\dfrac{3}{7}\cdot\left(\dfrac{15}{13}+\dfrac{11}{13}+1\right)\\ =-\dfrac{3}{7}\cdot\left(\dfrac{26}{13}+1\right)\\ =\dfrac{-3}{7}\cdot3\\ =\dfrac{-9}{7}\\ b.\dfrac{-1}{9}\cdot\dfrac{-3}{5}+\dfrac{5}{-6}\cdot\dfrac{-3}{5}-\dfrac{7}{2}\cdot\dfrac{3}{5}\\ =-\dfrac{3}{5}\cdot\left(\dfrac{-1}{9}+\dfrac{-5}{6}+\dfrac{7}{2}\right)\\ =-\dfrac{3}{5}\cdot\dfrac{23}{9}\\ =-\dfrac{23}{15}\)

\(3^{x+1}=27\)

\(3^{x+1}=3^3\)

\(\Rightarrow x+1=3\)

\(x=3-1\)

\(x=2\)

Vậy x = 2.

\(#Paciupibijd\)

\(3^{x+1}=27\)

\(\Rightarrow3^{x+1}=3^3\)

\(\Rightarrow x+1=3\)

\(\Rightarrow x=3-1\)

\(\Rightarrow x=2\)