All Questions
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FacuFeri 17/03/2019 at 14:11MathYou not Englishyou
enderman123_love roblox
13/03/2019 at 15:28
Quoc Tran Anh Le Coodinator
10/08/2018 at 03:30Maciej carries a bookmark with this table on it to help him remember his secret four digit number. If his secret number is 8526, all he has to do is to remember the words HELP. To retrieve his number, he looks up the letters of the word HELP and finds the corresponding digits in the top row of the table. Another example: The word LOVE can be used to help Maciej remember the secret number 2525. Maciej has to remember a new secret number. Only three of the following words produce this new number. Which one does not?
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 |
| A | B | C | D | E | F | G | H | I | J |
| K | L | M | N | O | P | Q | R | S | T |
| U | V | W | X | Y | Z |
Vui Ghét Nét
06/03/2019 at 23:48
Asta Cache
06/03/2019 at 13:51-
Nguyễn Thị Linh 06/03/2019 at 23:32
No, The letter math
Lê Anh Duy
04/03/2019 at 15:28-
FacuFeri 06/03/2019 at 05:13
We have : \(x^2-180x+8102=\left(x^2-180x+8100\right)+2=\left(x-90\right)^2+2\ge2\forall x\left(1\right)\)
Applying the Bunhiacopxki inequality , we have :
\(\left(\sqrt{x-89}+\sqrt{91-x}\right)^2\le\left(1+1\right)\left(x-89+91-x\right)\)
\(\Rightarrow\left(\sqrt{x-89}+\sqrt{91-x}\right)^2\le2.2=4\)
\(\Rightarrow\sqrt{x-89}+\sqrt{91-x}\le2\left(2\right)\)
Because \(\sqrt{x-89}+\sqrt{91-x}=x^2-180x+8102\)
So ( 1 ) ; ( 2 ) ; we have : \(\sqrt{x-89}+\sqrt{91-x}=x^2-180x+8102=2\)
Equal sign occurs \(\Leftrightarrow\sqrt{x-89}=\sqrt{91-x};x-90=0\left(3\right)\)
We have : \(\sqrt{x-89}=\sqrt{91-x}\) \(\Leftrightarrow x-89=91-x\Leftrightarrow x=90\left(4\right)\)
( 3 ) ; ( 4 ) \(\Rightarrow x=90\) is the result of the equation
Lê Anh Duy selected this answer. -
Huy Toàn 8A (TL) 06/03/2019 at 13:14
Đk : \(89\le x\le91\)
Applying the Bunhiacopxki inequality
We have : VT \(=1.\sqrt{x-89}+1.\sqrt{91-x}\le\sqrt{\left(1+1\right)\left(x-89+91-x\right)=2}\)
=> VT \(\le2\)
And VP = \(x^2-2.x.90+90^2+2=\left(x-90\right)^2+2\ge2\)
=> VP \(\ge2\ge\) VT
The sign "=" occurs when and only when:
\(\left\{{}\begin{matrix}\sqrt{x-89}=\sqrt{91-x}\\x-90=0\end{matrix}\right.\) => \(x=90\)(satisfy)
The answer is 90
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FacuFeri 05/03/2019 at 05:10
Tran Anh ??? Le Quoc Tran Anh ???
El matadora
03/03/2019 at 09:11-
Huy Toàn 8A (TL) 03/03/2019 at 13:37
El matodora : The Spam question
You should write the real question in English
Quoc Tran Anh Le Coodinator
02/03/2019 at 13:22-
Alone 03/03/2019 at 15:25The speed limit in this zone in feet per second is:
Quoc Tran Anh Le selected this answer.
88:60 x 15==22(feet) -
nguyễn kim tuyen 14/04/2019 at 02:40
22 feet
Quoc Tran Anh Le Coodinator
02/03/2019 at 13:21
Quoc Tran Anh Le Coodinator
02/03/2019 at 13:19-
Huy Toàn 8A (TL) 02/03/2019 at 13:29
C1: We have : 3x + 4x + 5x = x (3 + 4 + 5)
Replace x = 10 <=> 10 ( 3 + 4 + 5) = 10 . 12 = 120
C2 : 3x + 4x + 5x <=> 3 . 10 + 4 . 10 + 5 . 10 = 30 + 40 + 50 = 120
Quoc Tran Anh Le selected this answer.
