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Bài 4 trên cùng:
\(\dfrac{2x-y}{2}=\dfrac{x+2y}{3}\)
=>6x-3y=2x+4y
=>4x=7y
=>x/y=7/4
Đề 13:
Bài 2:
Áp dụng tính chất của dãy tỉ số bằng nhau, ta được:
\(\dfrac{x}{3}=\dfrac{y}{8}=\dfrac{z}{5}=\dfrac{4x+3y-2z}{4\cdot3+3\cdot8-2\cdot5}=\dfrac{96}{26}=\dfrac{48}{13}\)
Do đó: x=144/13; y=384/13; z=240/13
a): ta có AB^2 + AC^2 = 30^2 = 900 <=> AB = √(900 - AC^2)
AB:AC = 3:4 <=> AB = 3 * AC / 4
=> √(900 - AC^2) = 3 * AC / 4
<=> 900 - AC^2 = 9 * AC^2 / 16
<=> 14400 - 16 * AC^2 = 9 * AC^2
<=> 14400 = 25 * AC^2
<=> 576 = AC^2
<=> AC = 24
=> AB = 24 / 4 * 3 = 18
1. I usually stayed up late to watch football matches last year.
=> I used to stay up late to watch football matches last year.
2. There were some trees in the field.
=> There used to be some trees in the field.
3. She doesn't live with her parents anymore
=> She used to live with her parents more than now.
4. He is not a poor man anymore.
=> He used to be a rich man.
5. They didn't often go to the cinema every Sunday last year.
=> They didn't use to go to the cinama every Sunday last year.
6. My hair now is much longer than that in the past.
=> In the past my hair used to be shorter.
7. I don't have time to collect stamps as when I was in primary school.
=> I used to have much time to collect stamps when I was in primary school.
Nhiều vậy học copy bài à 😕 ít nhất cũng Hai Ba bài chứ. Nghĩ lại Đi mình lớp mấy rồi hùm 😦
Ko làm thì thôi nhé