Đáp án:
Giải thích các bước giải:
Bài 5:
Đặt `A=n^3+3n^2-n-3`
`A=n^2(n+3)-(n+3)`
`A=(n^2-1)(n+3)`
`A=(n-1)(n+1)(n+3)`
Vì n là số nguyên lẻ nên:
`n=2k+1\ (k \in \mathbb{N})`
Thế vào `A:`
`A=(2k+1-1)(2k+1+1)(2k+1+3)`
`A=2k(2k+2)(2k+4)`
`A=8k(k+1)(k+2)`
\(⇒ A\ \vdots\ 8\ (1)\)
Ta nhận thấy `k(k+1)(k+2)` là 3 số nguyên liên tiếp
\(⇒ A\ \vdots\ 6\ (2)\)
Từ `(1),(2)⇒ A` \(\vdots\) `48` (đpcm)
tìm txđ của hàm số y=sin(x-pi/2)+cos2x
8. “I must tell you about everything I found in this room,” said he. He said 9. “I am sick today,” said the boy. The boy said 10. The little girl said, “I was sick yesterday.” The little girl said 11. “My children don’t understand German,” said the woman. The woman said 12. She said to Mary, “I never forgot the good time we had last year.” She said to Mary
I.Fill in gaps with can, can’t or could. Then, say what they express in each sentence. 1. A: Mum, … I go on holiday with my friends this year? B: I’m afraid you … You’re too young. 2. A: Sir, I need to leave work early tonight, if that’s possible. B: You … leave early if you finish all your work first. 3. A: My mum always sail that I was a clever child. B: What do you mean? A: Well, I … read and write when I was four years old. 4. A: It’s raining, so we … go out tonight. B: Well, we’ll stay in then. A: But, I want to do something nice. I’m bored. B: We .. play chess . 5. A: Excuse me? B: Yes. A: … you tell me the time, please? B: Yes, it’s almost 2 o’clock.
6. Mary said, “I have been here for a few days. ” Mary said 7. Mr. Pike said to Daisy, “I didn’t meet your father yesterday.” Mr. Pike said
Ai đó giúp tôi với ạ. Xin cảm ơn nhiều lắm ạ
Em hay kể về một di sản văn hóa vật thể mà em biết(tối đa 200 chữ) Ai nhanh nhất có thưởng...
LÀM HỘ MÌNH VỚI Ạ. MÌNH CẢM ƠN NHIỀUUU
sửa hộ em nó vs =)))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))
Lm giúp mình chỉ bài 7 và bài 9 thôi nhé, mình cần gấp NL: tại mình ko cắt ra đc(;ŏ﹏ŏ)
giải giúp mình với mình đang cần gấp
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