Solution of Equation "no real roots" result - Solution of Equation "no real roots" result - Сообщения
#1 Опубликовано: 06.07.2022 16:26:55
Hi, I have an polynomial equation (x^3 specifically) which I want to get the roots for. The roots are there if I plug in values from WolframAlpha (https://www.wolframalpha.com/input?i2d=true&i=-21.2Power%5Bx%2C3%5D%2B19707.8Power%5Bx%2C2%5D%2B6628342.5x-1125000000), I also checked on excel by changing x=? I found a root of x~128 but SMath won't do it.
On SMath it says no results even after I removed the unit and everything?
I have used 'solve' function, but always get a "no real roots" message (see file attached).
Can someone help out?
Question.sm
Many thanks in advance!
On SMath it says no results even after I removed the unit and everything?
I have used 'solve' function, but always get a "no real roots" message (see file attached).
Can someone help out?
Question.sm
Many thanks in advance!
#2 Опубликовано: 06.07.2022 16:35:10
Hi. Try solve(f(x),x,0,1500)=1223.
Best regards
Alvaro
Best regards
Alvaro
#3 Опубликовано: 06.07.2022 17:12:34
Try to plot these kind of functions to see what is going on.
Your function is equals to zero around 1200.
Here is your solution with various solvers.
Regards
Question_answer.sm
Your function is equals to zero around 1200.
Here is your solution with various solvers.
Regards
Question_answer.sm
#4 Опубликовано: 06.07.2022 18:49:02
I have an polynomial equation ... which I want to get the roots for.
Your polynomial is doctored in yellow.
By inspection, the plot reveals complex roots, i.e: 2 complex roots.
Comment: respect preciously the Lagrange canonical order.
Cheers ... Jean.
Question Doctored.sm
#5 Опубликовано: 06.07.2022 21:58:06
Here is your complete answer by the way.
Good old maple saves the day again.
Regards
Good old maple saves the day again.
Regards
#6 Опубликовано: 07.07.2022 07:59:06
As it looks, if you create cubic at profusion,
the cubic roots solver will be a great companion.
It comes useful in PID techniques.
Polyroots is native in Smath.
the cubic roots solver will be a great companion.
It comes useful in PID techniques.
Polyroots is native in Smath.
#7 Опубликовано: 07.07.2022 08:38:23
... once your cubic in hand,
you can solve for a specific datum.
Cheers ... Jean.
you can solve for a specific datum.
Cheers ... Jean.
#8 Опубликовано: 11.07.2022 11:24:19
Hi Everyone,
Thank you for your replies they were very helpful. I really appreciate the people who went above and beyond to explain the various ways of getting the roots and even changing the datum.
It proved extremely helpful to plot the function where I quickly realized the difference between my SMath and WolframAlpha results. The 4th term 'x4' or 'c' is supposed to be a negative.
I though I was doing something wrong with inputting the data into SMath, but it was the function which I was inputting that was wrong.
In my program by changing "Qd" to a (negative) I got the following roots.
Lesson learned: Quadruple check your functions.
Question_finished.sm
Thank you for your replies they were very helpful. I really appreciate the people who went above and beyond to explain the various ways of getting the roots and even changing the datum.
It proved extremely helpful to plot the function where I quickly realized the difference between my SMath and WolframAlpha results. The 4th term 'x4' or 'c' is supposed to be a negative.
I though I was doing something wrong with inputting the data into SMath, but it was the function which I was inputting that was wrong.
In my program by changing "Qd" to a (negative) I got the following roots.
Lesson learned: Quadruple check your functions.
Question_finished.sm
#9 Опубликовано: 11.07.2022 13:10:43
#10 Опубликовано: 11.07.2022 13:32:16
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