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Quoc Tran Anh Le Coordinator
14/09/2018 at 07:08
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Sebastien starts with an 11 × 38 grid of white squares and colours some of them black. In each white square, Sebastien writes down the number of black squares that share an edge with it. Determine the maximum sum of the numbers that Sebastien could write down.

AIMO


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Summer Clouds
19/05/2017 at 14:19
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3
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Find the last digit of the power: \(2^{32}\).

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    Phan Thanh Tinh Coordinator 19/05/2017 at 16:23

    \(2^{32}=\left(2^4\right)^8=16^8\) has 6 as the last digit

    So the answer is 6

    Summer Clouds selected this answer.
  • ...
    Nguyễn Thị Thu Thủy 19/05/2017 at 20:33

    Summer Clouds 

    232=(24)8=168232=(24)8=168 has 6 as the last digit

    So the answer is 6

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    Nguyễn Thị Ý Nhi 22/05/2017 at 08:52

    6 là ansewr


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Summer Clouds moderators
21/07/2017 at 09:04
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The negative root of the equation \(\left(x+2\right)\left|x+3\right|=0\) is :.......?

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    Phan Thanh Tinh Coordinator 21/07/2017 at 17:56
    Lê Quốc Trần Anh was wrong.x can be equal to -6
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    Lê Quốc Trần Anh Coordinator 21/07/2017 at 12:01

    Sorry, can I answer again?

    \(\left(x+2\right)\left|x+3\right|=0\)

    => \(\left(x+2\right)=0\) or \(\left|x+3=0\right|\)

    => \(x=\left\{-2;-3;-6\right\}\)

    So the answer is \(x=\left\{-2;-3;-6\right\}\) (Phan Thanh Tinh miss one answer)

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    Phan Thanh Tinh Coordinator 21/07/2017 at 11:08

    \(\left(x+2\right)\left|x+3\right|=0\Rightarrow\left[{}\begin{matrix}x+2=0\\\left|x+3\right|=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=-2\\x=-3\end{matrix}\right.\)

    So,-2 and -3 are negative roots of the equation above.


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Summer Clouds moderators
08/08/2017 at 13:50
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Arturo invests $5000 in a mutual fund that gains 20% of its value in the first month, and then loses 20% of its value the following month. In dollars, how much is Arturo’s investment worth at the end of the second month?

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    WhySoSerious 08/08/2017 at 14:32

    In the first month the fund gains 20% so the total fund of him after the first month is :

    \(5000\cdot120\%=6000\)$

    At the end of second month Arturo loses 20% of its value, so Arturo's investment worth at that time is :

    \(6000\cdot80\%=4800\)$

    So the answer is 4800$.

    Selected by MathYouLike

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Summer Clouds moderators
31/08/2017 at 08:55
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There are four buttons in a row as shown below. Two of them show happy faces, and two of them show sad faces. If we press on a face, its expression turns to the opposite (e.g. a happy face turns into a sad face after the touch). In addition to this, the adjacent buttons also change their expressions. What is the least number of times you need to press a button in order to get all happy faces? 
undefined

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    Phan Thanh Tinh Coordinator 31/08/2017 at 10:17

    We need to press a button in order 3 times at least :

    S - H - S - H

    H - S - H - H

    H - H - S - S

    H - H - H - H

    Selected by MathYouLike

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Summer Clouds moderators
15/09/2017 at 08:55
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How many positive integers less than 40 are relatively prime to both 7 and 10?


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Summer Clouds moderators
16/10/2017 at 13:42
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 How many of the positive divisors of 6 to the power of 2006 have a units digit of 6?


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Cloud moderators
01/12/2017 at 14:27
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The hypotenuse of a 5-12-13 right triangle is the diameter of a semicircle containing the right angle vertex, as shown. What is the total area of the shaded regions? Express your answer to the nearest whole number. 
undefined

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    Nguyễn Hưng Phát 01/12/2017 at 18:29

    The area of the square triangle is:

         \(\dfrac{12.5}{2}=30\)

    The area of the semicircle is:

          \(\dfrac{\dfrac{13}{2}.\dfrac{13}{2}.3,14}{2}=\dfrac{26533}{400}=66,3325\)

    The total area of the shaded regions is:

           66,3325-30=36,3325\(\approx36\)

    Answer:36

    Selected by MathYouLike
  • ...
    Vũ Mạnh Hùng 02/12/2017 at 20:56

    The answer is 36

    it is correct?

  • ...
    Shirayuki Akagami 02/12/2017 at 12:38

    The area of the square triangle is:

         12.52 = 3012 . 52 = 30

    The area of the semicircle is:

          132.132.3,142 = 26533400 = 66,3325132.132.3,142 = 26533400 = 66,3325

    The total area of the shaded regions is:

           66,3325 - 30 = 36,33253636

    Answer:36


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Alone
01/01/2018 at 12:04
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Let M=\(\dfrac{2.1+1}{\left(1^2+1\right)^2}+\dfrac{2.2+1}{\left(2^2+2\right)^2}+.......+\dfrac{2.2015+1}{\left(2015^2+2015\right)^2}\).Prove that:M<1

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    Lê Quốc Trần Anh Coordinator 02/01/2018 at 21:33

    M = \(1-\dfrac{1}{2^2}+\dfrac{1}{2^2}-\dfrac{1}{3^2}+...+\dfrac{1}{2015^2}-\dfrac{1}{2016^2}\)

    M = \(1-\dfrac{1}{2016^2}=1-\dfrac{1}{4064256}=\dfrac{4064255}{4064256}\)

    Alone selected this answer.
  • ...
    FC Alan Walker 25/02/2018 at 14:34

    We have: \(\dfrac{2n+1}{\left(n^2+n\right)^2}=\dfrac{\left(n+1\right)^2-n^2}{n^2\left(n+1\right)^2}=\dfrac{1}{n^2}-\dfrac{1}{\left(n+1\right)^2}\)

    So: \(M=\dfrac{2.1+1}{\left(1^2+1\right)^2}+\dfrac{2.2+1}{\left(2^2+2\right)^2}+...+\dfrac{2.2015+1}{\left(2015^2+2015\right)^2}\)

                \(=1-\dfrac{1}{2^2}+\dfrac{1}{2^2}-\dfrac{1}{3^2}+...+\dfrac{1}{2015^2}-\dfrac{1}{2016^2}\)

                \(=1-\dfrac{1}{2016^2}< 1\)

  • ...
    FA Liên Quân Garena 08/01/2018 at 21:57

    M = 1−122+122−132+...+120152−120162

    M = 1−120162=1−14064256=40642554064256


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hanh nguyen thi
24/02/2018 at 16:38
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The product of 40 and a number m, is a 2-digit number that greater than 40. The value of m is

 


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Trigonometric
sin cos tan cot sinh cosh tanh
Lim-log

Combined operations

 

α β γ δ θ σ ∂ ε ω φ ϕ π μ λ Ψ ξ η χ ζ ι κ ν ψ Ω ρ τ υ Γ Δ Λ Φ Π Σ Υ Ξ ϑ Θ ς ϰ
∞ ⊻ ⩞ ⋎ ⋏ ≀ ∪ ⊎ ⋓ ∩ ⋒ ⊔ ⊓ ⨿ ⊗ ⊙ ⊚ ⊛ ⊘ ⊝ ⊕ ⊖ ⊠ ◯ ⊥
⇔ ⇒ ⇐ → ← ↔ ↑ ↓
Operations
+ - ÷ × ≠ = ⊂ ⊃ ⊆ ⊇ ≈ ∈ ∉ ∃ ∄ ≤ ≥ ± ∓ ≠ ∅ ≃ ≅ ≡ ⋮ ⋮̸ ∀
(□) [□] {□} |□|

The type of system

m×n 1×2 1×3 1×4 1×5 1×6
2×1 2×2 2×3 2×4 2×5 2×6
3×1 3×2 3×3 3×4 3×5 3×6
4×1 4×2 4×3 4×4 4×5 4×6
5×1 5×2 5×3 5×4 5×5 5×6
6×1 6×2 6×3 6×4 6×5 6×6

Recipe:

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