Giải thích các bước giải:
a) $(x - 3)$² = $16$
⇒ $(x - 3)$² = $(±4)$²
Xét trường hợp
TH$1$: $x - 3 = 4$
⇒ $x = 4 + 3$
⇒ $x = 7$
TH$2$: $x - 3 = -4$
⇒ $x = -4 + 3$
⇒ $x = -1$
Vậy x ∈ { $7, -1$ }
b) $(x + 2)$² = $25$
⇒ $(x + 2)$² = $(±5)$²
TH$1$: $x + 2 = 5$
⇒ $x = 5 - 2$
⇒ $x = 3$
TH$2$: $x + 2 = -5$
⇒ $x = -5 - 2$
⇒ $x = -7$
Vậy x ∈ { $-7, 3$ }
c) | x | = $0$
⇒ x = $0$
d) | x |= $10$
⇒ x ∈ { $10, -10$ }
e) | x - $1$ | = $3$
TH$1$: x - $1$ = $3$
⇒ x = $3 + 1$
⇒ x = $4$
TH$2$: x - $1$ = $-3$
⇒ x = $-3 + 1$
⇒ x = $-2$
Vậy x ∈ { $-2, 4$ }
g) | x + $2$ | = $6$
TH$1$: x + $2$ = $6$
⇒ x = $6 - 2$
TH$2$: x + $2$ = $-6$
⇒ x = $-6 - 2$
⇒ x = $-8$
Vậy x ∈ { $-8, 4$ }
h) $2^{3x+6}$ = $1$
⇒ $2^{3x+6}$ = $2^{0}$
⇒ $3x + 6 = 0$
⇒ $3x = 0 - 6$
⇒ $3x = -6$
⇒ $x = -6 : 2$
⇒ $x = -3$
Vậy x = $-3$
k) $3^{5x-10}$ = $1$
⇒ $3^{5x-10}$ = $3^{0}$
⇒ $5x - 10 = 0$
⇒ $5x = 0 - 10$
⇒ $5x = -10$
⇒ $x = -10 : 5$
⇒ $x = -2$
Vậy x = $-2$
Đáp án:
a) (x-3)²=16
(x-3)²=4²
x-3 =4
⇒x=7
b) (x+2)²=25
(x+2)²=5²
x+2 =5
⇒x=3
c)trị tuyệt đối x=0⇒x=0
d)trị tuyệt đối x=10⇒x=10 hoặc-10
e) trị tuyệt đối x-1=3
⇒x-1=3 hoặc x-1=-3
TH1:x-1=3⇒x=4
TH2:x-1=-3⇒x=-2
g)trị tuyệt đối x+2=6
⇒x+2=6 hoặc x+2=-6
TH1: x+2=6⇒x=4
TH2: x+2=-6⇒x=-8
1. Tìm x ∈ Q, biết: a) (x+1).(x+2) < 0 b) (x-2).(x+ $\frac{2}{3}$ ) > 0 Không copy nhá
giải thích tại sao lại chọn câu đấy
nói về môn học yêu thik ! khoảng 7 -10 dòng
Mn híup mik làm bài này với nha
Vẽ đậu mầm buồn Bo cần một người đàn ông mạnh mẽ để tâm sự :(
V. Write the opposite. 1. turn up (the radio)___ 2. put on (a coat)___ 3. forget (a name)___ 4. get better___ 5. stand up___ VI. 1. When I saw her she was walking ____ the lake. across through towards 2. Last night we ___ a cake for his birthday. made did paid 3. She always ___ a handbag. wears puts carries 4. Go ___ the supermarket and the bank is on your left. over past along 5. I ___broke my friend’s camera. luckily accidentally immediately 6. He looks ___his father. like as same 7. I looked ___ the new words in the dictionary. down through up 8. A: I love computer games. B: ____ do I! So Also Neither 9. I’m looking ___Jan’s baby while she’s out. forward after for 10. I gave ____ smoking two years ago. down off up 11. I am working very hard because I want to ____ at 50 and go travelling. retire separate leave 12. Did you know text-messaging was ____ by a Finnish company? discovered invented designed 13. I went to Morocco in August and it was ___ hot. In fact it was boiling. a bit quite incredibly 14. The lion looked asleep but it ___ jumped up and ran away. luckily accidentally suddenly 15. The little girl said she wanted to get married and ___ ten children. have get become VII. Complete the sentences with one word. 1. The student ___ me he had been in the school for a month. 2. A: Shall we go out for dinner? B: That’s OK. I ___ mind cooking. 3. I’m looking ___ Ben. Have you seen him? 4. I get on very __ with Jackie. She’s like a sister to me. 5. I do the same thing every day. It is so ___. I want to do something different and more exciting. 6. We walked ___ the bridge to see the ducks in the river. 7. I cooked the meal and my wife ____ the washing up. 8. Please don’t ___ a noise. The baby’s sleeping. 9. A: What are you doing here? B: I’m waiting ___ a friend. 10. The boy ___ that he wanted to dance with me. VIII. Underline the stressed syllable. 1. newspaper 2. kangaroo 3. invented 4. divorced 5. salary 6. elephant 7. towards 8. dolphin 9. imagination 10. directed IX. Match the words with the same sound. hope get tiger forget turn divorced discover wear enjoy finish 1. promise___ 2. dangerous___ 3. across___ 4. mosquito___ 5. whale___ 6. elephant____ 7. throw__ 8. earn__ 9. pretend____ 10. try___
Nhiệt phân một lượng MgCO3 sau một thời gian thu được chất rắn A và khí B. Hấp thu hết khí B vào dd NaOH thu được dd C vừa tác dụng với dd BaCl2 vừa tác dụng với dd NaOH. Hoà tan chất rắn A vào dd HCl dư thu được khí B và dd D. Cô cạn dd D thu được muối khan E. Điện phân nóng chảy E thu được kim loại M. Xác định thành phần A, B, C, D, E, M. Viết phương trình phản ứng.
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1859 × 3679= nhanh nha các bạn
I. 1. I got to the school at 12.00 but Maria’s lesson ____ (not finish yet). 2. This hotel ___ (build) a hundred years ago. 3. He told her he ____ (want) to see her again. 4. A: I didn’t see the Pyramids when I went to Egypt. B: Neither ____ (do) I. 5. I ____ (know) Pam for ten years. She’s my best friend. 6. If Jack really loved Sue, he ____ (ask) her to marry him. 7. A: How long ___ you ___ (be) afraid of water? B: Since I was a small child. 8. A: I ___ (not like) ice-cream. B: Neither do I. 9. The teacher asked me if I ___ (want) to take an exam. 10. A: Why are you going to the supermarket? B: ____ (buy) some bread. 11. The secretary asked me who I _______ (wait) for. 12. If they ___ (get) here before eight o’clock, we’ll go out for a meal. 13. This sports centre ____ (open) by the Queen in 1998. 14. BMW cars ___ (make) in Germany. 15. What would you do if you ___ (lose) your mobile phone? II. 1. It’s important to learn / learning a language when you’re young. 2. It’s too / enough hot to sit here. Let’s go inside. 3. Was / Did he use to play football for Liverpool? 4. When I was ill I couldn’t eat nothing / anything. 5. What have you seen / did you see at the cinema last night? 6. The concert might / will finish early. It depends how many songs they sing. 7. You shouldn’t / don’t have to sunbathe without suncream. 8. I’d like to go / going to London for a weekend. 9. I get on well with my parents / with my parents well. 10. They’ve lived in this town since / for 20 years. 11. You don’t have to / mustn’t pay to see the film. It's free. 12. He’s very interested in study / studying Art at university. 13. A: I love going out in the evening. B: So / Neither do I. 14. I might go/ to go to the party. I’m not sure. 15. If I don’t do my homework, my teacher will be / would be very angry. III. Complete the sentences with one word. 1. He hasn’t seen his brother ___ last November. 2. I ran into the shop and went ___ the stairs to the first floor. 3. ____you ask him, he’ll help us. 4. A: ____ they use to have a small shop in the town centre? B: Yes, but it closed two years ago. 5. He isn’t old ___ to learn to drive. You have to be 17. 6. I phoned Tim but he ____ already left. 7. The teacher ____ me if I knew the answer. 8. The picture was painted ___ the French painter, Monet. 9. I’m bored. There’s ____ to do in this town. 10. If I drink ___ many cups of coffee, I get a bad headache. IV. Underline the odd word(s) out. 1. football golf cycling tennis 2. retire earn miss get a job 3. physics maths chemistry biology 4. throw kick push shoot 5. wear put on try on carry 6. spider cow horse pig 7. get an email get home get a present get a salary 8. crocodile swan dolphin giraffe 9. an exam housework yoga your bed 10. rabbit bear crocodile tiger
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