Đáp án:
$81x^2+6yz-9y^2-z^2$
=$81x^2 - (9y^2-6yz+z^2)$
= $81x^2-(3y-z)^2$
=$(9x)^2 - (3y-z)^2$=$(9x-3y+z)(9x+3y-z)$
HỌC TỐT!
Giải thích các bước giải:
`c)81x²+6yz-9y²-z²`
`=81x²-(z²-6yz+9y²)`
`=(9x)²-(z-3y)²`
`=(9x-z+3y).(9x+z-3y)`
$#chúc tus học tốt nha!$
A. PHONETICS I. Choose the word whose underlined part is pronounced differently from that of the others 1. A. switch B. stomach C. champion D. catch 2. A. cloths B. improves C. lakes D. communicates 3. A. castle B. whistle C. hostel D. listen 4. A. change B. hungry C. angry D. single 5. A. ancient B. face C. page D. angle II. Choose the word whose stress pattern is different from that of the others 1. A. industry B. tornado C. natural D. injury 2. A. geography B. electronic C. scientific D. preparation 3. A. patient B. humor C. deny D. friendly 4. A. worried B. reserved C. polite D. arrive 5. A. mathematics B. economics C. politics D. automatics
He didn't help me with my homework
mn giải giúp em với ạ , em cảm ơn
Hãy đưa ra 5 lời khuyên về vấn đề sức khỏe (sử dụng MORE/ LESS ) ko đc trùng trong SGK nha ....
Part 6: Rewrite these sentences, keeping the original meaning: 1. Although she was very old, she looked very grateful. (In spite of) → …………………………………………………………………. 2. Peter enjoys scientific expedition, and Mary does, too. (Both…and) → …………………………………………………………………. 3. The weather was so dismal. They had to cancel the picnic immediately. (so) → …………………………………………………………………. 4. The film was not interesting. However, he tried to watch the whole film. (Although) → …………………………………………………………………. 5. Smallpox is a dangerous disease. Malaria is a dangerous disease. (Not only…but also) → …………………………………………………………………. 6. She doesn't want to go to their party. We don't want to go either. (Neither…nor) → …………………………………………………………………. 7. She gets up early to prepare breakfast so that her children can come to school on time. (Because) → …………………………………………………………………. 8. We could have dinner at home. We could also go out to eat. (either) → …………………………………………………………………. 9. He doesn’t like hip hop and pop music. (neither) → …………………………………………………………………. 10. My younger sister likes not only Vietnam’s songs but also Korea’s songs. (both … and) → ………………………………………………………………….
"Viết một đoạn văn tả dòng suối bằng tiếng anh" giúp em với ạ
Vẽ sơ đồ tư duy bài Đại từ ( Văn 7) đẹp , rõ , có màu sắc
1. The phone stopped ringing the moment I got down stairs. No sooner _______________________________________________ 2. He is determined to carry on working when he is 65. He has no ________________________________________________ 3. He was very sorry that he didn’t see Audrey on her trip to London. He greatly ______________________________________________ 4. She agreed to go out to dinner with him because she assumed he was not married. Had she __________________________________________________ 5. Everyone was surprised that the singer had very little money when he died. The singer had _____________________________________________
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Viết một đoạn văn 6-8 câu cảm nhận về vẻ đẹp của bài ca dao số " Ở đâu năm cửa ..." cảm ơn anh chị
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