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Nguyen Huu Ai Linh
07/12/2017 at 08:33
Answers
3
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75 + 75 x 3 = ?

Who tick me 5 tick I tick that guy 10 ticks.

  • ...
    Trần Quỳnh Anh 27/12/2017 at 13:07

    75+75.3

    = 75.(1+3)

    = 75.4

    = 300

  • ...
    Nguyen Huu Ai Linh 07/12/2017 at 17:34

    Opps! Sorry! That's :

    75 + 75 x 3

    = 75 + 225

    = 300

  • ...
    Nguyen Huu Ai Linh 07/12/2017 at 10:33

    75 + 75 x 3

    = 150 x 3

    = 450


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Lê Quốc Trần Anh Coordinator
04/01/2018 at 17:47
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0
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When creating a particular pattern, the designer begins with a line segment 1 unit long. Each successive stage is created by using congruent segments that are half as long as those in the previous stage. If you trace the design at Stage 4, how many units longer is it than the length of the design at Stage 1? 


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Lê Quốc Trần Anh Coordinator
04/03/2018 at 04:07
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1
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Max has eight identical cups. Each cup contains a different combination of nickels, dimes and quarters, each totaling 45 cents. Max randomly selects a cup. What is the probability that the cup he selects contains at least three dimes? Express your answer as a common fraction.

  • ...
    Lê Quốc Trần Anh Coordinator 07/03/2018 at 04:38

    ANSWER:

    There are 8 situations of the cup. Only two of the cups contain three or more dimes. Therefore, the probability that Max randomly selects one of these cups is 2/8 = 1/4.


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Lê Quốc Trần Anh Coordinator
06/05/2018 at 13:42
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1
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Prove that the $\sqrt{2}$ cannot be expressed in the form $\frac{m}{n}$ where $m$ and $n$ are rational.

  • ...
    Alone 06/05/2018 at 17:07

    Suppose \(\sqrt{2}\) can be expressed in the form \(\dfrac{m}{n}\) with (m,n)=1

    \(\Rightarrow\dfrac{m}{n}=\sqrt{2}\Rightarrow\dfrac{m^2}{n^2}=2\)\(\Rightarrow m^2=2n^2\)

    Because \(2n^2⋮2\) so \(m^2⋮2\Rightarrow m⋮2\)(1)

    \(\Rightarrow m^2⋮4\)\(\Rightarrow n^2⋮2\Rightarrow n⋮2\)(2)

    From (1) and (2),we have the assumption is wrong

    So \(\sqrt{2}\) can be expressed in the form \(\dfrac{m}{n}\)

    Lê Quốc Trần Anh selected this answer.

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Lê Quốc Trần Anh Coordinator
19/06/2018 at 02:23
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0
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Five wooden disks are numbered -3, -2, 1, 4 and 7. If two disks are chosen at random, without replacement, what is the probability that their product is negative? Express your answer as a common fraction.


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Lê Quốc Trần Anh Coordinator
23/07/2018 at 02:45
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1
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How many distinct three-letter strings can be formed using three of the five letters in the word SILLY?

Mathcounts

  • ...
    Tôn Thất Khắc Trịnh 23/07/2018 at 07:13

    SILLY has 5 letters
    S is used once
    I is used once
    L is used twice
    Y is used once
    So the number of distinct strings are \(\dfrac{5!}{1!1!2!1!}=60\)

    Selected by MathYouLike

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Kaya Renger Coordinator
05/08/2018 at 08:37
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0
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With a,b,c are three non-negative numbers that satisfy a + b + c = 3

Show that: \(\Sigma\left(a\sqrt{a+8}+2\right)\ge15\)


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Quoc Tran Anh Le Coordinator
01/01/2019 at 12:27
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If a race car is traveling at 99 mi/h, how many meters does it travel in a second, given that 0.305 meter = 1 foot? Express your answer as a decimal to the nearest tenth.

 

Mathcounts


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mark zuckerberg
19/03/2017 at 00:37
Answers
2
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The value of x in

\(\dfrac{x}{1\times2}+\dfrac{x}{2\times3}+\dfrac{x}{3\times4}+...+\dfrac{x}{1999\times2000}=1\)is?

simple equation

  • ...
    Phan Thanh Tinh Coordinator 23/03/2017 at 18:39

    \(\dfrac{x}{1.2}+\dfrac{x}{2.3}+\dfrac{x}{3.4}+...+\dfrac{x}{1999.2000}=1\)

    \(x\left(\dfrac{1}{1.2}+\dfrac{1}{2.3}+\dfrac{1}{3.4}+...+\dfrac{1}{1999.2000}\right)=1\)

    \(x\left(1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+...+\dfrac{1}{1999}-\dfrac{1}{2000}\right)=1\)

    \(x\left(1-\dfrac{1}{2000}\right)=1\)

    \(x.\dfrac{1999}{2000}=1\)

    \(x=\dfrac{2000}{1999}\)

    Selected by MathYouLike
  • ...
    FA KAKALOTS 03/02/2018 at 12:41

    x1.2+x2.3+x3.4+...+x1999.2000=1

    x(11.2+12.3+13.4+...+11999.2000)=1

    x(1−12+12−13+13−14+...+11999−12000)=1

    x(1−12000)=1

    x.19992000=1

    x=20001999


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Summer Clouds moderators
11/08/2017 at 08:47
Answers
1
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Of the 3 million people who auditioned for a television talent competition in the past 10 years, only 1% of 1% were selected to be contestants. How many people were selected to be contestants in this talent competition in the past 10 years?

  • ...
    Lê Quốc Trần Anh Coordinator 11/08/2017 at 09:01

    The number of people were selected to be contestants is: \(3000000.\left(1\%.1\%\right)=3000000.\left(0.01\%\right)=300\left(people\right)\)

    So the answer is: \(300people\)


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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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