c.

\(\left\{\begin{matrix} 9x-6y=4\\ 15x-10y=7\end{matrix}\right.\Leftrightarrow \left\{\begin{matrix} x=\frac{6y+4}{9}\\ 15x-10y=7\end{matrix}\right.\)

\(\Rightarrow 15.\frac{6y+4}{9}-10y=7\)

\(\Leftrightarrow \frac{5}{3}(6y+4)-10y=7\Leftrightarrow \frac{20}{3}=7\) (vô lý)

Do đó hpt vô nghiệm.

d.

\(\left\{\begin{matrix} 4x+5y=3\\ x-3y=5\end{matrix}\right.\Leftrightarrow \left\{\begin{matrix} 4x+5y=3\\ x=3y+5\end{matrix}\right.\Rightarrow 4(3y+5)+5y=3\)

\(\Leftrightarrow 17y+20=3\Leftrightarrow 17y=-17\Leftrightarrow y=-1\)

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

Vậy HPT có nghiệm $(x,y)=(2,-1)$

Các câu còn lại bạn làm theo pp tương tự.

1.

HPT \(\Leftrightarrow \left\{\begin{matrix} 5x-y=4\\ 3x-y=5\end{matrix}\right.\Leftrightarrow \left\{\begin{matrix} 5x-y=4\\ y=3x-5\end{matrix}\right.\)

\(\Rightarrow 5x-(3x-5)=4\Leftrightarrow 2x+5=4\Leftrightarrow 2x=-1\Leftrightarrow x=\frac{-1}{2}\)

\(y=3x-5=\frac{-3}{2}-5=\frac{-13}{2}\)

Vậy HPT có nghiệm $(x,y)=(\frac{-1}{2}, \frac{-13}{2})$

2.

HPT \(\Leftrightarrow \left\{\begin{matrix} 4xy+8x-6y-12=4xy-12x+54\\ 3xy-3x+3y-3=3xy+3y-12\end{matrix}\right.\)

\(\Leftrightarrow \left\{\begin{matrix} 20x-6y=66\\ -3x=-9\end{matrix}\right.\Leftrightarrow \left\{\begin{matrix} 6y=20x-66\\ x=3\end{matrix}\right.\Leftrightarrow \left\{\begin{matrix} x=3\\ y=-1\end{matrix}\right.\)

Vậy HPT có nghiệm $(3,-1)$

còn cần kh á

5 The white dress is cheaper than the black one

6 In spite of the bad weather, it did not delay the traffic

7 If you don't work hard, you will fail the exam

8 It takes me two hours to get to Hai Phong

9 What is the height of that building?

10 The water was too cold for the children to go swimming

11 Don't forget to wake me up at eight tomorrow morning

12 I am into going to the cinema with my friends at weekends

13 Ann is a dangerous driver

phét vừa thôi nướcnào mà biết tiêng việt lèo lèo thế

nói thiệt đó cậu ko tin thì đến nhà tớ

thế nhà cậu ở đang ở nước lào ?

   6/11 . 18/13 + 36/13 . 8/11 + 3/13

=(6/11+8/11) . (36/13.3/13+18/13)

=14/11.126/13

=1764/143

=

huheo giúp tớ đi tớ cho:3

giúp với:<

24+3(5-x)=27

3(5-x) = 27-24

3(5-x) = 3

5-x= 3:3

5 - x = 1

x= 4

~~~Học tốt ~~~

Chữ viết của mình hơi xấu, mong bạn thông cảm

Hello everyone, I'd like to tell you about my favourite food. It's beef noodle. It's made if rice, beef, and many kinds of herbs. I usually eat beef noodle in the morning. My favourite restaurant is Cuong Noodle. It's a small restaurant located on Tran Hung Dao street in Ho Chi Minh city. Whenever i eat beef noodle, it always makes me have a special taste. Hanoi capital is famous for beef noodle. What's more, it's also well-known for a lot of delicious foods. For example Omai, frilled rice... At home, my mother makes beef noodle very well. She often makes it when my family get together. We enjoy the happy time when we have beef noodle at home.

1B

2C

3A

4D

5C

6A

Chào em, em tham khảo nhé:

1. B

2. C

3. A

4. D

5. C

6. A

Chúc em học tốt.

1B

2C

3A

4D

5C

6A