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 #5
avatar+65 
+2

The hyperoperations are basically a sequence that extends the 3 basic functions everyone is familiar with.

Addition is hyperoperation 1

Multiplication is hyperoperation 2

Exponentiation is hyperoperation 3

Tetration is hyperoperation 4

and it continues on forever (although hyperoperations greater than or equal to 4 have problems with their domains).

 

Let f(x) be the 'n'th hyperoperation. You can get from hyperoperation 'n' to hyperoperation 'n+1' by setting the 'x' of f(x) to a certain value and then iterating f(x) 'x' times. That takes a lot of work, but for going from hyperoperation 'n' to hyperoperation 'n-1', you just need to use the formula \(f(1+{f}^{-1}(x))\), where \(f^{-1}(x)\) is the functional inverse of \(f(x)\). Using this, you can find out how to go from hyperoperation 'n' to hyperoperation 'n-2' or other values. Basically, you can go from hyperoperation 'n' to hyperoperation 'n-v', where 'v' is an integer.

 

Hyperoperation 'n-2' from hyperoperation 'n': \(f(1+f^{-1}(1+f(-1+f^{-1}(b))))\)

 

I then remembered something I did about a year ago. I set up this equation \(f(a)=f^2(b)\) and solved for \(f(b)\), and I got \(f^{0.5}(a)=f(b)\). Then I did it for the 3rd iteration, then the 4th, and so on. In other words, I learned how to get \(f^{\frac1n}(x)\) from \(f^n(x)\). So I figured that I could apply this to hyperoperations.


Basically, if you set up this equation \(g(1+g^{-1}(a))=f(1+f^{-1}(1+f(-1+f^{-1}(b))))\) ('n-1' and 'n-2' equations equal to each other) and manage to solve the right side for \(f(1+{f}^{-1}(x))\) (the 'n-1' equation), the left side will, consequently, turn from an 'n-1' equation into an 'n-0.5' equation. This would give us the ability to define fractional hyperoperations (and not just for 'n-0.5'), and if a useful, usable pattern is found, can lead to the generalization of all hyperoperations.

May 2, 2019
 #1
avatar+82 
+2

First, I need to find f –1(x), g –1(x), and ( f o g)–1(x):

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Inverting  f (x):

Inverting g(x):

Finding the composed function:   Copyright © Elizabeth Stapel 2002-2011 All Rights Reserved

Inverting the composed function:

Now I'll compose the inverses of  f(x) and g(x) to find the formula for (g–1 o f –1)(x):

Note that the inverse of the composition (( f o g)–1(x)) gives the same result as does the composition of the inverses ((g–1 o f –1)(x)). So I would conclude that

f (x) = 2x – 1 
    y = 2x – 1 
    y + 1 = 2x 
    (y + 1)/2 = x 
    (x + 1)/2 = y 
    (x + 1)/2 =  f –1(x)

g(x) = (1/2)x + 4 
    y = (1/2)x + 4 
    y – 4 = (1/2)x 
    2(y – 4) = x 
    2y – 8 = x 
    2x – 8 = y 
    2x – 8 = g –1(x) 

( f o g)(x) = f (g(x)) = f ((1/2)x + 4) 
    = 2((1/2)x + 4) – 1 
    = x + 8 – 1 
    = x + 7

( f o g)(x) = x + 7 
    y = x + 7 
    y – 7 = x 
    x – 7 = y 
    x – 7 = ( f o g)–1(x)

(g–1 o f –1)(x) = g–1( f –1(x)) 
    = g–1( (x + 1)/2 ) 
    = 2( (x + 1)/2 ) – 8 
    = (x + 1) – 8 
    = x – 7 = (g–1 o f –1)(x)

( f o g)–1(x) = (g–1 o f –1)(x)

While it is beyond the scope of this lesson to prove the above equality, I can tell you that this equality is indeed always true, assuming that the inverses and compositions exist — that is, assuming there aren't any problems with the domains and ranges and such.

May 2, 2019
 #1
avatar+26387 
+3

Lines with slopes -1 and -2 are drawn through the first quadrant point (a,b) forming one triangle

with a side on the x-axis and the other with one side on the y-axis.

What is the total area of the two shaded triangles? (Write you answers in terms of a and b)

\(\mathbf{b_1=\ ?}\)

\(\begin{array}{|rcll|} \hline y&=&-x+b_1 \quad | \quad P(a,b) \text{ on line} \\ b&=&-a+b_1 \\ \mathbf{b_1} &=& \mathbf{a+b} \\\\ \mathbf{y} &=& \mathbf{-x+(a+b)} \\ \hline \end{array}\)

 

\(\mathbf{b_2=\ ?}\)

\(\begin{array}{|rcll|} \hline y&=&-2x+b_2 \quad | \quad P(a,b) \text{ on line} \\ b&=&-2a+b_2 \\ \mathbf{b_2} &=& \mathbf{2a+b} \\\\ \mathbf{y} &=& \mathbf{-2x+(2a+b)} \\ \hline \end{array}\)

 

\(\mathbf{y=0}\\ \mathbf{c_x=\ ?} \)

\(\begin{array}{|rcll|} \hline 0 &=& -x_1+(a+b) \\ \mathbf{x_1} &=& \mathbf{a+b} \\\\ 0 &=& -2x+(2a+b) \\ 2x &=& 2a+b \\ \mathbf{x_2} &=& \mathbf{a+\dfrac{b}{2}} \\\\ c_x &=& x_1-x_2 \\ &=& a+b - \left(a+\dfrac{b}{2} \right) \\ \mathbf{c_x} &=& \mathbf{\dfrac{b}{2}} \\ \hline \end{array}\)


\(\mathbf{x=0}\\ \mathbf{c_y=\ ?}\)

\(\begin{array}{|rcll|} \hline y_1 &=& -0 +(a+b) \\ \mathbf{y_1} &=& \mathbf{a+b} \\\\ y_2 &=& -2\cdot 0+(2a+b) \\ &=& 2a+b \\ \mathbf{y_2} &=& \mathbf{2a+b} \\\\ c_y &=& y_2-y_1 \\ &=& 2a+b-(a+b) \\ \mathbf{c_y} &=& \mathbf{a} \\ \hline \end{array}\)

 

\(\mathbf{A_x=\ ?} \)

\(\begin{array}{|rcll|} \hline A_x &=& \dfrac{c_xh_x}{2} \quad | \quad h_x = b,\qquad c_x = \dfrac{b}{2} \\\\ &=& \dfrac{\dfrac{b}{2}\cdot b}{2} \\\\ \mathbf{A_x} &=& \mathbf{\dfrac{b^2}{4}} \\ \hline \end{array}\)

 

\(\mathbf{A_y=\ ?}\)

\(\begin{array}{|rcll|} \hline A_y &=& \dfrac{c_yh_y}{2} \quad | \quad h_y = a,\qquad c_y = a \\\\ &=& \dfrac{a\cdot a}{2} \\\\ \mathbf{A_y} &=& \mathbf{\dfrac{a^2}{2}} \\ \hline \end{array}\)

 

\(\mathbf{A=\ ?}\)

\(\begin{array}{|rcll|} \hline A&=& A_x + A_y \\ &=& \dfrac{b^2}{4} + \dfrac{a^2}{2} \\ \mathbf{A} &=& \mathbf{\dfrac{1}{2}\cdot \left( a^2 + \dfrac{b^2}{2} \right) } \\ \hline \end{array} \)

 

laugh

May 2, 2019
 #5
avatar+6251 
+1
May 2, 2019

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