Câu 1:
`14x²y-21xy²+28x²y²`
`=7xy(2x-3y+4xy)`
`→` Chọn `A`
Câu 2:
`12x-9-4x²`
`=-(4x²-12x+9)`
`=-[(2x)²-2.2x.3+3²]`
`=-(2x-3)²`
`→` Chọn `B`
Câu 3:
`3x²-3xy-5x+5y`
`=(3x²-3xy)-(5x-5y)`
`=3x(x-y)-5(x-y)`
`=(3x-5)(x-y)`
Câu 4:
`5x²-4x+10xy-8y`
`=(5x²+10xy)-(4x+8y)`
`=5x(x+2y)-4(x+2y)`
`=(x+2y)(5x-4)`
`→` Chọn `C`
Câu 5:
`45²+40²-15²+80.45`
`=(45²+80.45+40²)-15²`
`=(45²+2.45.40+40²)-15²`
`=(45+40)²-15²`
`=85²-15²`
`=(85+15)(85-15)`
`=100.70`
`=7` `000`
`→` Chọn `D`
Câu 6:
`mn³-1+m-n³`
`=(mn³-n³)+(m-1)`
`=n³(m-1)+(m-1)`
`=(n³+1)(m-1)`
Câu 7:
`4xy-4xz-y+z`
`=(4xy-4xz)-(y-z)`
`=4x(y-z)-(y-z)`
`=(y-z)(4x-1)`
Câu 8:
`x³-2x²+x`
`=x(x²-2x+1)`
`=x(x-1)²`
Câu 9:
`(3x^5-2x^3+4x^2):2x^2`
`=(3x^5:2x^2)+[(-2x^3):2x^2]+(4x^2:2x^2)`
`=3/2x^3-x+2`
Một mảnh đất HCN có kích thước dài 50m, rộng 40m. Sau khi đào ao hình vuông có cạnh 20 m và làm nhà có chiều dài 20m, chiều rôgj 10m thì diện tích còn lại là bao nhiêu Chỉ cần ddáp án thôi ạ
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Giúp mình vs mn .mình đánh giá 5 *
Giúp mình bài này với : (x-1) ² < x(x-7)+6
Rút gọn a,√11 + 4√7 - √11- 4√7 b, √19 - 8√3 + √19 + 8√3 c, √9 + 4√2 + √9 - 4√2 d,√28 - 6√3 - √28 + 6√3 e, √21 - 12√3 - √21 + 12√3 f, √29 + 12√5 - √29 - 12√5 g, √5 + 2√6 - √5 + 2√6 h, √8 - 2√15 + √8 + 2√15
một bể nước dạng hình hộp chữ chữ nhật chứa đầy nước được 2250m3 . biết chiều dài bể là 45m chiều rộng bể là 25m . hỏi khi chứa đầy nước thì mực nước trong bể cao bao nhiêu mét ?
CHo mn câu dễ lấy điểm nè VÌ dễ nên làm 2 câu nhoa giải chi tiết ra giúp mình
Mong cs lời giải ạ Mk đg cần gấp vote cho b nào xong trc 5sao
B. Read the passage carefully, then choose the correct answers. Having a best friend to confide in can bring a positive effect on our emotional health. An evening out with the closest friend may be the best guarantee of a good time. In fact, our best friend can prevent us from developing serious psychological problems such as depression and anxiety. Best friendship evolves with time - we cannot go out and pick our best friend. We become friends with people who share common interests – at school or through hobbies, for example. Best friends have usually known each other for years and stuck together through good and bad times. If you haven't got one, perhaps you are being too distant from people, or focusing too much on your work. 41. A best friend can ________. a. give us a healthy life b. go out with us in the evening c. spend much time finding d. share joy and sadness with us 42. Close friends need to ________. a. study at the same school b. have the same interests c. pursue the same hobbies d. spend time together 43. According to the passage, ________. a. it takes a lot of time to make close friendships b. we can go out and choose a good friend easily c. best friends have good and bad times d. It’s very difficult to make lasting friendships 44. The word 'one' in the last paragraph refers to ________. a. good time b. bad time c. a friendship d. a close friend 45. Which of the following sentences is not mentioned? a. We often have satisfaction being with a close friend. b. the ties of close friendship will never be broken. c. An unsociable person may not have a close friend. d. Friendships need time to develop
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