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how can i solve this equation i keep get error

2 vues (au cours des 30 derniers jours)
amina shafanejad
amina shafanejad le 14 Déc 2015
clc,clear;
syms x
eqn=-15730900+(-1473100)+(501831/(1+x))+(501831/(1+x)^2)+(501831/(1+x)^3)+...
+(501831/(1+x)^4)+(501831/(1+x)^5)+(501831/(1+x)^6)+(501831/(1+x)^7)+...
+(501831/(1+x)^8)+(501831/(1+x)^9)+(501831/(1+x)^10)==0;
solx=solve(eqn,x)
this is my equation and i cant take the value for x im wonder why
  2 commentaires
Walter Roberson
Walter Roberson le 14 Déc 2015
What error do you get?
Those continuation lines would have to be immediately after the previous lines; you show a blank line between the lines of the eqn and that is not permitted syntax.
If you are using an earlier version of the Symbolic Toolbox, before about R2011b (I think) you might need to remove the "==0"
John D'Errico
John D'Errico le 14 Déc 2015
Note that there will surely be no analytical solution.

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John D'Errico
John D'Errico le 14 Déc 2015
As I pointed out, there will surely be no analytical solution. You should expect that with near certainty, as this is the equivalent of a high order polynomial.
I see no error however. Only the indication (from solve, in the form of the results it yields) that it was unable to compute analytical roots.
solve(eqn)
ans =
1/root(z^10 + z^9 + z^8 + z^7 + z^6 + z^5 + z^4 + z^3 + z^2 + z - 1564000/45621, z, 1) - 1
1/root(z^10 + z^9 + z^8 + z^7 + z^6 + z^5 + z^4 + z^3 + z^2 + z - 1564000/45621, z, 2) - 1
1/root(z^10 + z^9 + z^8 + z^7 + z^6 + z^5 + z^4 + z^3 + z^2 + z - 1564000/45621, z, 3) - 1
1/root(z^10 + z^9 + z^8 + z^7 + z^6 + z^5 + z^4 + z^3 + z^2 + z - 1564000/45621, z, 4) - 1
1/root(z^10 + z^9 + z^8 + z^7 + z^6 + z^5 + z^4 + z^3 + z^2 + z - 1564000/45621, z, 5) - 1
1/root(z^10 + z^9 + z^8 + z^7 + z^6 + z^5 + z^4 + z^3 + z^2 + z - 1564000/45621, z, 6) - 1
1/root(z^10 + z^9 + z^8 + z^7 + z^6 + z^5 + z^4 + z^3 + z^2 + z - 1564000/45621, z, 7) - 1
1/root(z^10 + z^9 + z^8 + z^7 + z^6 + z^5 + z^4 + z^3 + z^2 + z - 1564000/45621, z, 8) - 1
1/root(z^10 + z^9 + z^8 + z^7 + z^6 + z^5 + z^4 + z^3 + z^2 + z - 1564000/45621, z, 9) - 1
1/root(z^10 + z^9 + z^8 + z^7 + z^6 + z^5 + z^4 + z^3 + z^2 + z - 1564000/45621, z, 10) - 1
Again, that was completely expected. However, nothing stops you from getting approximate roots.
vpa(solve(eqn))
ans =
-1.6661435339699159760690274098319
-0.17803633410337122738678393539001
- 0.82944078945054912679553055169416 + 0.67487342116657470095168018942751i
- 1.2392357796067300876301190456248 - 0.63453525124017787853359333001222i
- 1.5503593102427657212185969586246 - 0.38032263725340143579333271938087i
- 1.5503593102427657212185969586246 + 0.38032263725340143579333271938087i
- 1.2392357796067300876301190456248 + 0.63453525124017787853359333001222i
- 0.82944078945054912679553055169416 - 0.67487342116657470095168018942751i
- 0.44428946799323473628513677400307 - 0.47475279125570655866734145566345i
- 0.44428946799323473628513677400307 + 0.47475279125570655866734145566345i

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