b. th1: 5-x=2x-1 nếu 5-x>0 => x< 5

5-x=2x-1

-x-2x=-1-5

-3x= -6

x= 2 (chọn)

th2: 5-x=-2x-1 nếu 5-x<0 => x>5

5-x=-2x-1

-x+2x= -1-5

x= -6 (loại)

S={2}

Vậy giá trị của P là:

2.2-1= 3

a. <=> \(\dfrac{2.\left(x-2\right)}{\left(x+1\right)\left(x-2\right)}\)+\(\dfrac{x+1}{\left(x+1\right)\left(x-2\right)}\)+\(\dfrac{6}{\left(x+1\right)\left(x-2\right)}\)= \(\dfrac{3}{x-2}\)

<=> \(\dfrac{2.\left(x-2\right)}{\left(x+1\right)\left(x-2\right)}\)+\(\dfrac{x+1}{\left(x+1\right)\left(x-2\right)}\)+ \(\dfrac{6}{\left(x+1\right)\left(x-2\right)}\)= \(\dfrac{3.\left(x+1\right)}{\left(x+1\right)\left(x-2\right)}\)

<=> 2.(x-2) + x + 1 + 6= 3x + 3

<=> 2x - 4 + x + 1 +6 - 3x - 3= 0

<=> 0x =0

<=> x=0

Vậy P= \(\dfrac{3}{x-2}\)

a. vì AB//CD => góc ABD=góc BDC

xét tam giác ADB và tam giác BCD có:

góc DAB=góc DBC (gt)

góc ABD= góc BDC (cmt)

=> tam giác ADB ~ tam giác BCD (c.c)

b. vì tam giác ADB ~ tam giác BCD 

=> \(\dfrac{AD}{BC}\)=\(\dfrac{AB}{BD}\)=\(\dfrac{DB}{CD}\)

=> BC= \(\dfrac{AD.BD}{AB}\)= \(\dfrac{4.6}{3}\)= 8(cm)

=> CD=  \(\dfrac{BD^2}{AB}\)= \(\dfrac{6^2}{3}\)= 12 (cm)

1. Paula asked Jack to help him.

2. Mike asked Mary if she was free next Saturday.

3. She asked me if i had gone out with Lan the day before.

4. Dave asked Peter if he had eaten Saigon rolls.

5. Helen wanted to know if George loved her.

6. Hung asked Nam if he would go to the park the next day.

7. Ann asked what i was going to study. 

8. Bill asked what country i came from.

9. Mary asked how i would use english in the future.

10. my brother asked what train i was going to get.

11. The traveler asked how long it took to get to London.

12. he asked me why i hadn't come to class the day before.

13. Peter asked who put the salt in his cup of coffee.

14. she asked me why i came there late.

15. he asked the girl if she played the piano.

16. Maryam wanted to know if i was having a good time there.

1. he said that he was a student.

2. they said that they were learning english then.

3. Tom said that  his friend was coming next week.

4. they said that they should overcome that difficulty. 

5. Nam said that he could solve that problem.

6. Dick said that he had to leave at eight.

7. he told me that he had something to show me then. 

8. she said that she was leaving there for Hue the next day.

9. Tom said to her that he would come with her as soon as he was ready. 

10. the father said to us that he had to go then.

Số cây cam là:

\(\dfrac{4}{3}\).12= 16 (cây)

Tổng số cây là: 

12: \(\dfrac{30}{100}\)= 40 (cây)

Số cây mít là:

40.\(\dfrac{25}{100}\)= 10 (cây)

Số cây hồng xiêm là:

40-12-10-16= 2 (cây)

gọi số thứ nhất là a

     tổng của hai số thứ hai và thứ 3 là a+959

theo đề ta có: a + a + 959=5307

                      2a = 4348

                        a= 2174

Vậy số thứ nhất là 2174

Tiếp tục, gọi số thứ hai là b

                    số thứ ba là b+255

Ta có: b + b + 255= 5307- 2174

          2b = 3133 - 255

          2b= 2878

            b= 1439

Vậy số thứ hai là 1439

Số thứ ba là: b+255= 1439+255= 1694

Vậy số thứ ba là 1694