Cho 3 số thực a,b,c thỏa mãn \(\frac{a}{2017}=\frac{b}{2018}=\frac{c}{2019}\)

Chứng minh: \(4\cdot\left(a-b\right)\cdot\left(b-c\right)=\)\(\left(a-c\right)^2\)

Use the words given below to make questions. Ask your friend about his/her picture and listen to the answers.

Now, your friend will ask you questions about your picture. Answer his/her questions.