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 #1
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+5

Hi NinjaDragons98,

 

Here are the graphs.  I have also included a colour coded line at the centre of the temperature limits.

Red         Los Angeles

Green     Osaka

Blue        Buenos Aires

 

 

https://www.desmos.com/calculator/d2xfeenjdv

 

 

 

23)  Osaka (B green) has the biggest temperature variation becasue at 20.71 degrees it has the biggest amplitude.

 

24) You can see from the graph that Osaka has the coldest temperatures so it is most likely to snow in winter.

ALSO

The lowest sin(anything) is is -1

so the lowest temperatures are 

              Los Angeles   = -8.086+76.08 = 68 degrees

              Osaka            = -20.71+68.97 = 48 degrees

              Buenos Aires = -13.03+72.38 = 59 degrees

so you can see from the algebra that Osaka gets the coldest.

 

25)  Explain why the function for Buenos Aires has a positive horizonatal shift as opposed to the negative horizontal shift for Osaka and Los Angeles.

Los Angeles and Osaka are in the Northern Hemisphere and Buenos Aires is int the Southern hemisphere.

Los Angeles     y=8.086sin(0.01863t-2.507)+76.08

Osaka              y=20.71sin(0.0168t-1.945)+68.97

Buenos Aires   y=13.03sin(0.01710t+1.331)+72.38

 

If there was no shift - like the black graph then The hottest day would be about 1st April.

The southern hemisphere had its hottest day earlier than that.  The positive shift  number actually moves the graph in the negative direction.

The northern hemisphere has its hottest day elater than that.  The negative shift  number actually moves the graph in the positive direction.

 

Here is another graph.  I have superimposed a sine wave that has no horizontal shift. It is the black one.

To make it easy to compare I have made the centre line comparable to the others and the period is one year. 

Incidental to make the period a year I made the coefficient of t equal to 2pi/364=0.01726

 

 

26)  When will Los Angeles (red) and Osaka (greeen) have the same daily high temp.

From the graph,

The red and green graphs intersect at about (138,77) and (264,81)

138/364*12 = 4.5494505494505495   That is the middle of April  Day 138

264/364*12 = 8.7032967032967033   That is the middle of  August,  Day 264

 

27)  Logic tells me that they have more chance of all being the same temp in the middle of Spring or Autumn.

So, from the choices,  that would be April 25th.

From the graphs I can see that they have the most chance of being the same between day 107 and day 138

Both these days are in April so again it will be April 25th.

 

28)  The vertical shift from 0 degrees for Osaka is 68 degrees (this will be the middle of the temperaure range).

This is less than the other 2 so overall Osaka will be the coldest.

 

This is answered in probably more detail than you needed NinjaDragon but hopefully you will be able to make sense of it.

:)

 

Feel free to ask question.

laughfrowncool

Nov 27, 2016
 #1
avatar
+5

Well, I don't blame you. For instance, here is a technical definition of a "tensor", if you can understand it. Good luck to you.

 

An nth-rank tensor in m-dimensional space is a mathematical object that has n indices and m^n components and obeys certain transformation rules. Each index of a tensor ranges over the number of dimensions of space. However, the dimension of the space is largely irrelevant in most tensor equations (with the notable exception of the contracted Kronecker delta). Tensors are generalizations of scalars (that have no indices), vectors (that have exactly one index), and matrices (that have exactly two indices) to an arbitrary number of indices.
Tensors provide a natural and concise mathematical framework for formulating and solving problems in areas of physics such as elasticity, fluid mechanics, and general relativity.
The notation for a tensor is similar to that of a matrix (i.e., A = (a_(ij))), except that a tensor a_(ijk...), a^(ijk...), a_i ^(jk) ..., etc., may have an arbitrary number of indices. In addition, a tensor with rank r + s may be of mixed type (r, s), consisting of r so-called "contravariant" (upper) indices and s "covariant" (lower) indices. Note that the positions of the slots in which contravariant and covariant indices are placed are significant so, for example, a_μν ^λ is distinct from a_μ ^νλ.
While the distinction between covariant and contravariant indices must be made for general tensors, the two are equivalent for tensors in three-dimensional Euclidean space, and such tensors are known as Cartesian tensors.

Nov 27, 2016
 #1
avatar
0

First, this how I interpreted your equaton.
2*4sqrt(5x^2 - 8x + 1) + 4 =33*2sqrt(5x^2 - 8x), solve for x
Second, this is a very long and complicated solution, but it is ACCURATE!

Solve for x:
4 + 8 sqrt(5 x^2 - 8 x + 1) = 66 sqrt(5 x^2 - 8 x)

Subtract 4 from both sides:
8 sqrt(5 x^2 - 8 x + 1) = 66 sqrt(5 x^2 - 8 x) - 4

Raise both sides to the power of two:
64 (5 x^2 - 8 x + 1) = (66 sqrt(5 x^2 - 8 x) - 4)^2

Expand out terms of the left hand side:
320 x^2 - 512 x + 64 = (66 sqrt(5 x^2 - 8 x) - 4)^2

(66 sqrt(5 x^2 - 8 x) - 4)^2 = 16 - 34848 x + 21780 x^2 - 528 sqrt(5 x^2 - 8 x):
320 x^2 - 512 x + 64 = 16 - 34848 x + 21780 x^2 - 528 sqrt(5 x^2 - 8 x)

Subtract 64 - 512 x + 320 x^2 - 528 sqrt(5 x^2 - 8 x) from both sides:
528 sqrt(5 x^2 - 8 x) = 21460 x^2 - 34336 x - 48

Raise both sides to the power of two:
278784 (5 x^2 - 8 x) = (21460 x^2 - 34336 x - 48)^2

Expand out terms of the left hand side:
1393920 x^2 - 2230272 x = (21460 x^2 - 34336 x - 48)^2

Expand out terms of the right hand side:
1393920 x^2 - 2230272 x = 460531600 x^4 - 1473701120 x^3 + 1176900736 x^2 + 3296256 x + 2304

Subtract 460531600 x^4 - 1473701120 x^3 + 1176900736 x^2 + 3296256 x + 2304 from both sides:
-460531600 x^4 + 1473701120 x^3 - 1175506816 x^2 - 5526528 x - 2304 = 0

Factor constant terms from the left hand side:
-16 (28783225 x^4 - 92106320 x^3 + 73469176 x^2 + 345408 x + 144) = 0

Divide both sides by -16:
28783225 x^4 - 92106320 x^3 + 73469176 x^2 + 345408 x + 144 = 0

Eliminate the cubic term by substituting y = x - 4/5:
144 + 345408 (y + 4/5) + 73469176 (y + 4/5)^2 - 92106320 (y + 4/5)^3 + 28783225 (y + 4/5)^4 = 0

Expand out terms of the left hand side:
28783225 y^4 - 37058408 y^2 + 298197904/25 = 0

Substitute z = y^2:
28783225 z^2 - 37058408 z + 298197904/25 = 0

Divide both sides by 28783225:
z^2 - (37058408 z)/28783225 + 298197904/719580625 = 0

Subtract 298197904/719580625 from both sides:
z^2 - (37058408 z)/28783225 = -298197904/719580625

Add 343331400873616/828474041400625 to both sides:
z^2 - (37058408 z)/28783225 + 343331400873616/828474041400625 = 300250368/33138961656025

Write the left hand side as a square:
(z - 18529204/28783225)^2 = 300250368/33138961656025

Take the square root of both sides:
z - 18529204/28783225 = (528 sqrt(1077))/5756645 or z - 18529204/28783225 = -(528 sqrt(1077))/5756645

Add 18529204/28783225 to both sides:
z = 18529204/28783225 + (528 sqrt(1077))/5756645 or z - 18529204/28783225 = -(528 sqrt(1077))/5756645

Substitute back for z = y^2:
y^2 = 18529204/28783225 + (528 sqrt(1077))/5756645 or z - 18529204/28783225 = -(528 sqrt(1077))/5756645

Take the square root of both sides:
y = sqrt(18529204/28783225 + (528 sqrt(1077))/5756645) or y = -sqrt(18529204/28783225 + (528 sqrt(1077))/5756645) or z - 18529204/28783225 = -(528 sqrt(1077))/5756645

Substitute back for y = x - 4/5:
x - 4/5 = sqrt(18529204/28783225 + (528 sqrt(1077))/5756645) or y = -sqrt(18529204/28783225 + (528 sqrt(1077))/5756645) or z - 18529204/28783225 = -(528 sqrt(1077))/5756645

Add 4/5 to both sides:
x = 4/5 + sqrt(18529204/28783225 + (528 sqrt(1077))/5756645) or y = -sqrt(18529204/28783225 + (528 sqrt(1077))/5756645) or z - 18529204/28783225 = -(528 sqrt(1077))/5756645

Substitute back for y = x - 4/5:
x = 4/5 + sqrt(18529204/28783225 + (528 sqrt(1077))/5756645) or x - 4/5 = -sqrt(18529204/28783225 + (528 sqrt(1077))/5756645) or z - 18529204/28783225 = -(528 sqrt(1077))/5756645

Add 4/5 to both sides:
x = 4/5 + sqrt(18529204/28783225 + (528 sqrt(1077))/5756645) or x = 4/5 - sqrt(18529204/28783225 + (528 sqrt(1077))/5756645) or z - 18529204/28783225 = -(528 sqrt(1077))/5756645

Add 18529204/28783225 to both sides:
x = 4/5 + sqrt(18529204/28783225 + (528 sqrt(1077))/5756645) or x = 4/5 - sqrt(18529204/28783225 + (528 sqrt(1077))/5756645) or z = 18529204/28783225 - (528 sqrt(1077))/5756645

Substitute back for z = y^2:
x = 4/5 + sqrt(18529204/28783225 + (528 sqrt(1077))/5756645) or x = 4/5 - sqrt(18529204/28783225 + (528 sqrt(1077))/5756645) or y^2 = 18529204/28783225 - (528 sqrt(1077))/5756645

Take the square root of both sides:
x = 4/5 + sqrt(18529204/28783225 + (528 sqrt(1077))/5756645) or x = 4/5 - sqrt(18529204/28783225 + (528 sqrt(1077))/5756645) or y = sqrt(18529204/28783225 - (528 sqrt(1077))/5756645) or y = -sqrt(18529204/28783225 - (528 sqrt(1077))/5756645)

Substitute back for y = x - 4/5:
x = 4/5 + sqrt(18529204/28783225 + (528 sqrt(1077))/5756645) or x = 4/5 - sqrt(18529204/28783225 + (528 sqrt(1077))/5756645) or x - 4/5 = sqrt(18529204/28783225 - (528 sqrt(1077))/5756645) or y = -sqrt(18529204/28783225 - (528 sqrt(1077))/5756645)

Add 4/5 to both sides:
x = 4/5 + sqrt(18529204/28783225 + (528 sqrt(1077))/5756645) or x = 4/5 - sqrt(18529204/28783225 + (528 sqrt(1077))/5756645) or x = 4/5 + sqrt(18529204/28783225 - (528 sqrt(1077))/5756645) or y = -sqrt(18529204/28783225 - (528 sqrt(1077))/5756645)

Substitute back for y = x - 4/5:
x = 4/5 + sqrt(18529204/28783225 + (528 sqrt(1077))/5756645) or x = 4/5 - sqrt(18529204/28783225 + (528 sqrt(1077))/5756645) or x = 4/5 + sqrt(18529204/28783225 - (528 sqrt(1077))/5756645) or x - 4/5 = -sqrt(18529204/28783225 - (528 sqrt(1077))/5756645)

Add 4/5 to both sides:
x = 4/5 + sqrt(18529204/28783225 + (528 sqrt(1077))/5756645) or x = 4/5 - sqrt(18529204/28783225 + (528 sqrt(1077))/5756645) or x = 4/5 + sqrt(18529204/28783225 - (528 sqrt(1077))/5756645) or x = 4/5 - sqrt(18529204/28783225 - (528 sqrt(1077))/5756645)

4 + 8 sqrt(5 x^2 - 8 x + 1) ≈ 12.0148
66 sqrt(5 x^2 - 8 x) ≈ 4.01479:
So this solution is incorrect

4 + 8 sqrt(5 x^2 - 8 x + 1) ⇒ 4 + 8 sqrt(1 - 8 (4/5 + sqrt(18529204/28783225 - (528 sqrt(1077))/5756645)) + 5 (4/5 + sqrt(18529204/28783225 - (528 sqrt(1077))/5756645))^2) = 4 + (8 sqrt(1172917 - 528 sqrt(1077)))/1073 ≈ 12.0148
66 sqrt(5 x^2 - 8 x) ⇒ 66 sqrt(5 (4/5 + sqrt(18529204/28783225 - (528 sqrt(1077))/5756645))^2 - 8 (4/5 + sqrt(18529204/28783225 - (528 sqrt(1077))/5756645))) = (132 sqrt(5397 - 132 sqrt(1077)))/1073 ≈ 4.01479:
So this solution is incorrect

4 + 8 sqrt(5 x^2 - 8 x + 1) ≈ 12.1341
66 sqrt(5 x^2 - 8 x) ≈ 12.1341:
So this solution is correct

4 + 8 sqrt(5 x^2 - 8 x + 1) ⇒ 4 + 8 sqrt(1 - 8 (4/5 + sqrt(18529204/28783225 + (528 sqrt(1077))/5756645)) + 5 (4/5 + sqrt(18529204/28783225 + (528 sqrt(1077))/5756645))^2) = 4 + (8 sqrt(1172917 + 528 sqrt(1077)))/1073 ≈ 12.1341
66 sqrt(5 x^2 - 8 x) ⇒ 66 sqrt(5 (4/5 + sqrt(18529204/28783225 + (528 sqrt(1077))/5756645))^2 - 8 (4/5 + sqrt(18529204/28783225 + (528 sqrt(1077))/5756645))) = (132 sqrt(5397 + 132 sqrt(1077)))/1073 ≈ 12.1341:
So this solution is correct

The solutions are:
Answer: |x = 4/5 + sqrt(18529204/28783225 + (528 sqr(1077))/5756645                                              or x = 4/5 - sqrt(18529204/28783225 + (528 sqrt(1077))/5756645)

Nov 27, 2016
Nov 26, 2016

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