Finding Real Solutions for x-tanh ax = 0 with a>1

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In summary: When x=0, y=1 and there on as x is increasing, value of y is decreasing..When x=0, y=1 and there on as x is increasing, value of y is decreasing..
  • #1
physicsblr
13
0
Can anybody help me with this equation?

I need answer for the question, how many real solutions does the equation x-tanh ax = 0 have for a>1?
 
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  • #2
welcome to pf!

hi physicsblr! welcome to pf! :smile:

draw the graph, for 0 ≤ x ≤ 1 (since tanh can't be ≥ 1) …

what is the slope of tanhax ? :wink:
 
  • #3
Is it a?
 
  • #4
I have a doubt. x=0 is a root of this eq and since its a linear eq, it has only 1 root?
 
  • #5
tiny-tim said:
what is the slope of tanhax ? :wink:
physicsblr said:
Is it a?

no, of course not :redface:

how do we find the slope of a graph?​
 
  • #6
oh! slope is zero.
 
  • #7
how do we find the slope of a graph?
 
  • #8
first derivative of the equation = 0 gives the slope.
 
  • #9
physicsblr said:
first derivative of the equation = 0 gives the slope.

well, first derivative of the equation gives the slope

so the slope of tanhax is … ? :smile:
 
  • #10
1-tanh2 ax; so for that eq. tanh2 ax = 0 is final result.
 
  • #11
(try using the X2 button just above the Reply box :wink:)
physicsblr said:
1-tanh2 ax

(= sech2ax)

no

use the chain rule​
 
  • #12
am getting 2 cases. either a=1 or sech2 ax=1.
 
  • #13
physicsblr said:
Can anybody help me with this equation?

… how many real solutions does the equation x-tanh ax = 0 have for a>1?
physicsblr said:
am getting 2 cases. either a=1 or sech2 ax=1.

uhh? :redface:

what question are you answering? :confused:

(and you still need to find the correct derivative of tanh(ax))
 
  • #14
Am unable to get it properly, am no good in mathematics. If u can pls explain it and give an answer since I have an entrance exam next week, I will be very thankful.
 
  • #15
i] draw the graph of y = x for 0≤x≤1 …

that'll be a square with a diagonal​

ii] find the derivative of y = tanh(ax)

(that is not sech2(ax) … do it again, using the chain rule)

iii] the derivative equals the slope of the graph of y = tanh(ax), so plot the values at x = 0 and 1, and use the slope to find how it starts and finishes …

what do you get? :smile:
 
  • #16
When x=0, y=1 and there on as x is increasing, value of y is decreasing..
 
  • #17
physicsblr said:
When x=0, y=1 and there on as x is increasing, value of y is decreasing..

uhh? :confused:

what was unclear about? …
tiny-tim said:
i] draw the graph of y = x for 0≤x≤1 …

that'll be a square with a diagonal​

ii] find the derivative of y = tanh(ax)

(that is not sech2(ax) … do it again, using the chain rule)

iii] the derivative equals the slope of the graph of y = tanh(ax), so plot the values at x = 0 and 1, and use the slope to find how it starts and finishes …

what do you get? :smile:
 

1. What is the purpose of finding real solutions for x-tanh ax = 0 with a>1?

The purpose of finding real solutions for x-tanh ax = 0 with a>1 is to solve for the values of x that satisfy the equation and to understand the behavior of the hyperbolic tangent function.

2. How is the hyperbolic tangent function related to this equation?

The hyperbolic tangent function, tanh x, is the inverse of the hyperbolic sine function, sinh x. It is used to model the growth or decay of a quantity over time. In this equation, the hyperbolic tangent function is used to find the values of x that make the equation equal to 0.

3. What is the process for finding real solutions for this equation?

The process for finding real solutions for x-tanh ax = 0 with a>1 involves first setting the equation equal to 0 and then using algebraic techniques to isolate the variable x. This may include factoring, using the quadratic formula, or other methods. Once x has been isolated, the solutions can be found by solving for x using the appropriate techniques.

4. Are there any restrictions on the values of a for this equation?

Yes, there is a restriction on the values of a for this equation. The value of a must be greater than 1 in order for the hyperbolic tangent function to be defined. This is because the hyperbolic tangent function has an asymptote at y=1, so a value of a less than 1 would result in an undefined function.

5. Are there any real-life applications for this equation?

Yes, the hyperbolic tangent function and its inverse are used in various fields such as physics, engineering, and economics to model real-life situations involving growth or decay. For example, the hyperbolic tangent function can be used to model the charging or discharging of a capacitor in an electrical circuit.

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