Đáp án+Giải thích các bước giải:
`5)3.5^(2x-6)=75`
`=>5^(2x-6)=75:3=25`
`=>5^(2x-6)=5^2`
`=>2x-6=2`
`=>2x=2+6=8`
`=>x=8:2=4`
`6)3^(x+1) -3^x=18`
`=>3^x .3 -3^x=18`
`=>3^x .(3-1)=18`
`=>3^x .2=18`
`=>3^x=18:2=9`
`=>3^x=3^2`
`=>x=2`
$\\$
`5,`
`3 . 5^{2x-6} = 75`
`->5^{2x-6}=75 : 3`
`->5^{2x-6}=25`
`-> 5^{2x-6}=5^2`
`->2x-6=2`
`->2x=2+6`
`->2x=8`
`->x=8:2`
`->x=4`
Vậy `x=4`
`6,`
`3^{x+1} - 3^x=18`
`->3^x .3 - 3^x = 18`
`->3^x . (3-1)=18`
`->3^x . 2 =18`
`->3^x=18 :2`
`->3^x=9`
`->3^x=3^2`
`->x=2`
Vậy `x=2`
Do you like wearing jeans? Why?
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You have decided to enter a short-story writing competition. The rules of the competition say that the story must begin with these words: Looking back on that day, we all agreed it was our/ my greatest victory.
Vẽ một em mèm. NL: Bạn nèo hôm trước là quỷ í nhờ :>
Bài 1: Tính a) (5x + 3yz)2 b) (y2x – 3ab)2 c) (x2 – 6z)(x2 + 6z) d) (2x – 3)3 e) (a + 2b)3 g) (x2 + 3)(x4 + 9 – 3x2) h) (y – 5)(25 + 2y + y2 + 3y) Bài 2: Rút gọn biểu thức: a) B = (x + y)2 – 2(x + y)(x – y) + (x – y)2 = x2 + 2xy + y2 – 2x2 + 2y2 + x2 – 2xy + y2 = 4y2 b) C = (x + y)3 - (x – y)3 – 2y3
Câu 12:Cho dãy chuyển hóa sau: CuCl2 Cu(OH)2 CuSO4. Các chất X, Y lần lượt là A. Mg(OH)2, H2SO4. B.Ca(OH)2, Na2SO4. C. NaOH, H2SO4. D.KOH, K2SO4
Em hãy tìm hiểu và cho biết Liên Xô đã giúp đỡ Việt Nam xây dựng những công trình gì?
I: Choose the best answer 1. I saw a very ..( excite / excited / exciting/ excitable) movie in the cinema yesterday. 2. Dictionaries are very…..( used/ useful / uselessness/ use) books. 3. Jackie and I had a….( wonderful/ wondered/ wondering/ wonder) time in France last summer. 4. My brother is a very….( careful/ careless/ cared/ carefully) person. He keeps losing things wherever he goes. 5. These factories have discharged a lot of ……( poison / poisonous) chemicals into the rivers. 6. Jack finds his job very ………( bored/ boring) 7. The child has remained so…….. ( selfish / unselfish/ unselfishness) because he has never shared any thing with other children. 8. We should eat more….. ( health / healthy) food . 9. The girl looks very …( attract / attractive / attractively). 10. His new job sounds more …( interested/ interesting / interestingly) 11. To make our work more….( effect / effective / effectively), we need to work together.
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Cho 19,5 gam Zn tác dụng hoàn toàn vơi dung dịch HCl. Thể tích khí thu được ở đktc là ( Zn = 65, H= 1, Cl = 35,5)
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