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Vinil7 [7]
3 years ago
6

At a party, everyone shook hands with everybody else. These were 66 handshakes. How many people were at the party?

Mathematics
1 answer:
nignag [31]3 years ago
7 0
In general, with n+1 people, the number of handshakes is the sum of the first n consecutive numbers: 1+2+3+ ... + n. Since this sum is n(n+1)/2, we need to solve the equation n(n+1)/2 = 66. This is the quadratic equation n2+ n -132 = 0. Solving for n, we obtain 11 as the answer and deduce that there were 12 people at the party.
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nadezda [96]
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Softa [21]

Answer:

4i.

Step-by-step explanation:

To find the flux through the square, we use the divergence theorem for the flux. So Flux of F(x,y) = ∫∫divF(x,y).dA

F(x,y) = hxy,x - yi

div(F(x,y)) = dF(x,y)/dx + dF(x,y)dy = dhxy/dx + d(x - yi)/dy = hy - i

So, ∫∫divF(x,y).dA = ∫∫(hy - i).dA

= ∫∫(hy - i).dxdy

= ∫∫hydxdy - ∫∫idxdy

Since we are integrating along the boundary of the square given by −1 ≤ x ≤ 1, −1 ≤ y ≤ 1, then

∫∫divF(x,y).dA = ∫₋₁¹∫₋₁¹hydxdy - ∫₋₁¹∫₋₁¹idxdy

= h∫₋₁¹{y²/2}¹₋₁dx - i∫₋₁¹[y]₋₁¹dx

= h∫₋₁¹{1²/2 - (-1)/2²}dx - i∫₋₁¹[1 - (-1)]dx

= h∫₋₁¹{1/2 - 1)/2}dx - i∫₋₁¹[1 + 1)]dx

= 0 - i∫₋₁¹2dx

= - 2i[x]₋₁¹

= 2i[1 - (-1)]

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= 2i(2)

= 4i  

7 0
3 years ago
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Here it is...........................

4 0
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<img src="https://tex.z-dn.net/?f=5x%20%20%2B%2011%287x%20-%203" id="TexFormula1" title="5x + 11(7x - 3" alt="5x + 11(7x - 3"
Murljashka [212]

82x - 33 ✅

\large\mathfrak{{\pmb{\underline{\red{Step-by-step\:explanation}}{\orange{:}}}}}

5x + 11(7x - 3) \\  = 5x + 77x - 33 \\  = 82x - 33

\large\mathfrak{{\pmb{\underline{\orange{Happy\:learning }}{\orange{.}}}}}

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d1i1m1o1n [39]

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