quy đồng các p/s sau 3/7 4/9 8/21

Mn ơi giúp mk vs ạ . Mk cảm ơn

Cho a, b, c ∈ [0; 1] và a + b + c = 2. Tìm giá trị lớn nhất của biểu thức P = a ² + b ² + c ²

Mn giúp e vs ạ!Em cảm ơn Bài 3 Đề 4

Giúp mình vs mình đag cần gấp mai đi học rùi

Một người đi từ A đến B rồi lại đi từ B về A mất 3 giờ 41 phút đoạn đường AB dài 94 km gồm một đoạn lên dốc tiếp đó là đoạn đường bằng tiếp đó là một đoạn đường xuống dốc hỏi đoạn đường dài bao nhiêu km nếu vận tốc của người đó là 4km /h lúc đi đoạn đường bằng là 5km/h lúc xuống dốc là 6km/h

Cho biết phát biểu nào dưới đây là đúng: A.gốc cacbonat(CO3) và sunfat(SO4) hoá trị 1 B.gốc photphat(PO4) hoá trị 2 C.gốc clorua(Cl) và nitrat(NO3) hoá trị 3 D.nhóm hiđroxit(OH) hoá trị 1

Tìm và sửa lỗi sai 1.From at nine in the morning until four afternoon Mr.Tuan works in the fields with his father. 2.There is fewer work in the evening than there is in the morning 3.He was absent from work yesterday because of he was ill 4.You must try to make these children clean their tooth. 5.There is many furniture made of wood in the sitting room. 6.I am terrible sorry.I didn't mean to break your windows 7.On the back of the shool yard there is a bigh apple tree 8.We left our luggate at the station and go to find something to eat 9.I'm going out now and I will be back about a hour 10.She used to walking to school when he was a child Giúp mình vs ạ,đang cần gấp,hứa vote 5* và cảm ơn

đường kính của một bánh xe ô tô là 0,8 m Tính chu vi của bánh xe đó ô tô sẽ đi được bao nhiêu mét nếu bánh xe lăn trên mặt đất 10 vòng 80 vòng 1200 vòng. Tính diện tích hình tròn

Ex2:choose the correct sentence among A,B,C or D which has the same meaning as the give one 1.Eight years ago we started writing to each other A.We have rarely written to each years B.Eight years is a long time for us to write to each other C.We have to each other eight years ago D.We have been writing to each other for eight years 2.The boy was so lazy that he couldn’t stay up late to learn his lessons A.The boy was lazy enough not to stay up late to learn his lessons B.The boy was too lazy to stay up late to learn his lessons C.The boy was lazy enough but he stayed up late to learn his lessons D.The boy was lazy enough to stay up learn his lesson 3.My father is tired of seeing any violent films A.My father hasn’t seen a violent film B.My father has enjoyed all the violent films he has ever seen C.My father is worried about missing the next violent film D.My father never wants to see another violent film 4.As soon as he waved his hand ,she turned away A.He saw her turn away and he waved his hand B.No sooner had he waved his hand than she turned away C.She turned away because he waved his hand too early D.Although she turned away,he waved his hand 5.John wishes he had remembered to send Mary a Christmas card A.John regrets not to send Mary a Christmas card B.John regrets forgetting not to send Mary a Christmas card C.John regrets not remembering sending Mary a Christmas card D.John regrets forgetting to send Mary a Christmas card 6.My father hasn’t smoked cigarettes for a month A.It’s a month since my father last smoked cigarettes B.It’s a month ago that my father smoked cigarettes C.It’s a month that my father hasn’t smoked cigarettes D. It’s a cigarettes that my father smoked a month ago 7.Having finished their word,the workers expected to be paid A.The workers expected to be paid because they had finished their B.Having their work finishing, the workers expected to be paid C.Having expected to be paid ,the works finished their work D.Having been finished their word, the workers expected to be paid 8.Mr.Brow bought this car five years ago A .Mr .Brown started to buy this car five years B.It have been five years when Mr.Brown has bought this car C.Mr.Brown has had this car five years D.It is five years ago since Mr.Brown has bought this car 9.John used to write home once a week when he was any abroad A.John dosen’t write home once a week any longer B.John enjoyed being written home every week when he was abroad C.John never forgot to write a weekly letter home when he was abroad D.When he was abroad he rememeberd to write home when he was abroad 10.I have’t enjoyed myself so much so much for years A.It’s years since I enjoyed myself so much B.It’s years since I have enjoyed myself so much C.It’t was years since I had enjoy myself so much D.It has been years since I have enjoyed myself so much