Giúp mk với ạ, mk cảm ơn Mn nhiều 
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7N
lm giúp mk bài 3 với bài 4 với ạ, mk đng cần gấp, cảm ơn mn rất rất nhiều ạ !!!!
3
24 tháng 10 2021
Bài 3:
1, Áp dụng t/c dtsbn:
\(\dfrac{x}{6}=\dfrac{y}{4}=\dfrac{z}{3}=\dfrac{z-x}{3-6}=\dfrac{-21}{-3}=7\\ \Rightarrow\left\{{}\begin{matrix}x=42\\y=28\\z=21\end{matrix}\right.\)
2, Áp dụng t/c dtsbn:
\(\dfrac{x}{3}=\dfrac{y}{5}=\dfrac{z}{7}=\dfrac{2x+3y-z}{6+15-7}=\dfrac{-14}{14}=-1\\ \Rightarrow\left\{{}\begin{matrix}x=-3\\y=-5\\z=-7\end{matrix}\right.\)
24 tháng 10 2021
Bài 4:
Áp dụng tính chất của dãy tỉ số bằng nhau, ta được:
\(\dfrac{x}{\dfrac{1}{2}}=\dfrac{y}{\dfrac{1}{3}}=\dfrac{z}{\dfrac{1}{4}}=\dfrac{x+y+z}{\dfrac{1}{2}+\dfrac{1}{3}+\dfrac{1}{4}}=\dfrac{130}{\dfrac{13}{12}}=120\)
Do đó: x=60; y=40; z=30
NA
1
6 tháng 7 2021
Bạn nên đăng những câu khó nhất hoặc bạn lọc ra những câu tương tự nhau để bản thân có thể vận dụng nhé!
7N
Giúp mk với, mk đng cần rất rất gấp ạ, cảm ơn mn rất rất nhiều ạaaaaaaaaa !
0
2 tháng 3 2023
Câu 6:
a: =12x^2+4x-3x-1-5x^2+15x-x^2+7x-12
=6x^2+23x-13
b: =5x^2+5x-2x-2-3x^3+3x^2+9x-2x(x^2-9x+20)
=-3x^3+8x^2+14x-2-2x^3+18x^2-40x
=-5x^3+26x^2-26x-2
17 tháng 12 2020
In my house , I have a my room . It is the best room for me . I love it very much .I can store a lot of my important things in it. I will clean the room from time to time. There was a small bed in my room, which was just enough for me to sleep alone. There's also a small cupboard in the room to put up my clothes. Next to the bed where I slept, there was a white carpet under the small round table. That table was where I used to play chibi dolls. Ah, forgot the bookshelf on the headboard. The bookshelf is neatly lined with thick novels.Seeing me keep the room clean, my parents are very pleased.they kept complimenting me.I find it essential to keep the rooms in order.I love my room and I want the other rooms to be that.
18 tháng 12 2020
In my house, there are five rooms: a living room,a bathroom,a kitchenand two bedrooms.But my favourite room is my bedroom.It's comfartable.There is a bed,a wardrobe,a desk,two fans,two lights and two shelves
22 tháng 3 2022
6. They would rather Nam didn't smoke in the office.
7. You should practice speaking English every day.
8. What did you talk to him last night?
9. It isn't easy to learn English in a short time.
20. Your room is larger and more comfortable than ours.
\(9,=\dfrac{\sqrt{5}+1-\sqrt{5}+1}{\left(\sqrt{5}-1\right)\left(\sqrt{5}+1\right)}=\dfrac{2}{4}=\dfrac{1}{2}\\ 10,=\dfrac{\sqrt{5}+2+\sqrt{5}-2}{\left(\sqrt{5}-2\right)\left(\sqrt{5}+2\right)}=2\sqrt{5}\\ 11,=\dfrac{8+6\sqrt{2}-8+6\sqrt{2}}{\left(4-3\sqrt{2}\right)\left(4+3\sqrt{2}\right)}=\dfrac{12\sqrt{2}}{-2}=-6\sqrt{2}\\ 12,=\dfrac{2+\sqrt{6}+2-\sqrt{6}}{\left(2-\sqrt{6}\right)\left(2+\sqrt{6}\right)}=\dfrac{4}{-2}=-2\\ 13,=\sqrt{2}-1+\sqrt{2}+3=2\sqrt{2}+2\\ 14,=2-\sqrt{3}+\sqrt{3}-1=1\\ 15,=3-\sqrt{5}+\sqrt{5}-2=1\)