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a) 5x-15y= 5(x-3y)

b) 3/5x²+5x⁴-x²y

= x²(3/5+5x²-y)

bn có chép sai đầu bài ko z

a) (a+b)(a+b)² = (a+b)³

= a³+3a²b+3ab²+b³

b) (2x-y)²(2x-y) = (2x-y)³

= (2x)³-3.(2x)².y+3.2x.y²-y³

=8x³-12x²y+6xy²-y³

c) (3x+2y)(3x+2y)² = (3x+2y)³

= (3x)³+3.(3x)².2y+3.3x.(2y)²+(2y)³

= 27x³+54x²y+36xy²+8y³

3.

a, (2y- 1)³= (2y)³-3.(2y)².1+3.2y.1²-1³

= 8y³-12y²+6y-1

b, (3x²+2y)³=(3x²)³+3.(3x²)².2y+3.3x².(2y)²+1³

=27x⁶+54x⁴y+36x²y²+1

c, ( 1/3x-2)³=(1/3x)³-3.(1/3x)².2+3.1/3x.2²-2³

=1/27x³-2/3x²+4x-8

4.

a, -x³+3x³-3x+1=1-3x+3x³-x³

=1-3.1².x+3.1.x³-x³

=(1-x)³

b,64-48x+12x²-x³=4³-3.4².x+3.4.x²-x³

=(4-x)³

1. That television was bought by my father two weeks ago. 2. An art exhibition will be organized by their school next month. 3. we were given this watch by our mother two days ago. 4. This soup should be served when it is still hot. 5. The tet holiday will be celebrated by millions of Vietnamese people next month. 6. You will be asked several questions by the police tomorrow. 7. The napkins are washed in the hotel everyday. 8. we were told That Mary was sick. 9. The concerts are usually held at the university by the students. 10. Two children were found in the forest by the police this morning.

Gọi quãng đường AB là x (x >0; km)

Thời gian ôtô đó đi từ A->B là x/60 (h)

Vận tốc lúc về ôtô đi là 60+20=80 (km)

Thời gian ôtô đó lúc về đi được là x/80 (h)

Vì thời gian về ít hơn thời gian đi là 1h nên ta có PT:

x/60-x/80=1

<=> 4x/240-3x/240=240/240

=> 4x-3x=240

<=> x=240 (TMĐK)

Vậy quãng đường AB dài 240 km.

tính BC, BH, A. là sao

x(x-3)-4x+12=0

<=> x(x-3)-4(x-3)=0

<=> (x-3)(x-4)=0

<=> x-3=0 <=>x=3

x-4=0 <=>x=4

Vậy phương trình có tập nghiệm là S = 3;4

1.He said we were his best friend.

2.Nam said Lan wanted to come here but she wasn't very well.

3. He said to friends he must go home then.

4.Lan said she didn't known hơ to do these exercises.

5.Nien asked Hoa if Hoa has many friends.

6.Thanh said to her teacher she would finish her exercises at home.

7.Tom said he was student.

8.Nga to her brother she couldn't answer this question.

9.Charles said he was living in London then.

10.Johnny said to me he didn't known what Fred was doing.

11.She said she would answer the phone.

12.July said John wanted to come here but he wasn't very well.

13.Susan said her sister was coming to see her the following week.

14.Judy said to me she was going away for a fews day. She would phone me when she got back.