# Items tagged with solvesolve Tagged Items Feed

### Problem with gamma as variable...

November 21 2015
1 4

 (1)

 (2)

 (3)

 (4)

 (5)

 (6)

how can i solve this problem?

### Problem with solving system...

November 16 2015
0 1

How can I solve the following system in Maple for $S_1$ and $S_{i+1}$? I have the code written, but it is giving me nothing as output.

eq1 := Q-A*S[1]*C/X+B*D*(sum(S[j], j = 2 .. i+1))/Y-r[1]*S[1] = 0;
eq2 := A*S[i-1]*C/X-A*S[i]*C/X-B*S[i]*D/Y-r[1]*S[i] = 0;
eq3 := A*S[i]*C/X-B*S[i+1]*D/(Y+S[i+1])-r[2]*S[i+1] = 0;
solve({eq1, eq2, eq3}, {S[1], S[i+1]});

The only non-constants in the system are the $S_j$'s for $j = 1, \ldots, i+1$.

Here is the system in math mode:
$$Q-\frac{AC}{X}S_1-r_1 S_1 +\frac{BD}{Y}\sum\limits_{j=2}^{i+1}S_j = 0 \\ \frac{AC}{X}S_{i-1} - \frac{AC}{X}S_i - \frac{BD}{Y}S_i - r_1 S_i = 0\\ \frac{AC}{X}S_i - \frac{BD S_{i+1}}{Y+S_{i+1}} - r_2 S_{i+1} = 0$$

I have a head start on it by hand, but it's too cumbersome to complete.

Basically, my strategy is to solve for $S_{i+1}$ as a function of $S_1$ and some constants. Then to plug in $S_2, \ldots, S_{i+1}$ in the summation and solve for $S_1$ as a function of constants. Then I would obtain $S_{i+1}$ as a function of constants itself.

Thanks for any help.

### Four equations in four unknowns...

November 16 2015
0 3

 >
 (1)
 >
 (2)
 > diff((2), y);
 (3)
 > diff((3), y);
 (4)
 >
 (5)
 > diff((5), x);
 (6)
 > diff((6), x);
 (7)
 >
 (8)
 > diff((8), x);
 (9)
 > diff((9), y);
 (10)
 (11)
 > -(1/16)*Pi^2*sin((1/4)*Pi*x)*(c__1*cosh((1/4)*Pi*y)+c__3*y*cosh((1/4)*Pi/y)+c__4*y*sinh((1/4)*Pi*y))=0;
 (12)
 > eval( (12), [x = 0]);
 (13)
 >
 (14)
 > eval( (14), [x = 20]);
 (15)
 >
 (16)
 > eval( (16), [y = 9]);
 (17)
 > evalf[5]( (17) );
 (18)
 >
 (19)
 > eval( (19), [y = -9]);
 (20)
 > evalf[5]( (20) );
 (21)
 >
 (22)
 > eval( (22), [y = 9]);
 (23)
 > evalf[5]( (23) );
 (24)
 >
 (25)
 > eval( (25), [y = -9]);
 (26)
 > evalf[5]( (26) );
 (27)
 > s:=solve({sin(.78540*x)*(362.25*c__1+0.84938e-3*c__3+4182.6*c__4) = 0,sin(.78540*x)*(362.25*c__1-0.84938e-3*c__3+4182.6*c__4) = -1.*sin(.25000*Pi*x),-.78540*cos(.78540*x)*(461.22*c__1+.99617*c__3+4738.2*c__4) = 0,-.78540*cos(.78540*x)*(-461.22*c__1+.99617*c__3-4738.2*c__4) = 0},{c1,c2,c3,c4});
 (28)
 >

November 12 2015
0 1

Assume that I have r:= -6x+3y+23x2-4xyz+7z. By using coeffs(r,x,'k') I can find the coefficients of 1, x, and x2

What should I write to get the conditions that make the coefficient of x zero? How can I just pick the coefficient of x, and solve it.

I have several coefficients but the answer of this question will help me.

### How to find all the roots? ...

November 11 2015
1 2

i type on maple like this:

solve(2*cos(0.5*x)*sin(0.5*x)*cos(3.775*x)+2.2075*((cos(0.5*x))^2)*sin(3.775*x)-0.453*((sin(0.5*x))^2)*sin(3.775*x)=0);

but it said the solutions may have been lost

thanks before

### Why won't Maple solve this?...

November 10 2015
1 8

Hi

I'm trying to solve this in maple:

solve({0.001=x*exp(0.6/(n*0.026)), 0.01=x*exp(0.68/(n*0.026))},{x,n})

Wolfrom alpha can do it: http://www.wolframalpha.com/input/?i=solve%28%7B0.001%3Dx*exp%280.6%2F%28n*0.026%29%29%2C+0.01%3Dx*exp%280.68%2F%28n*0.026%29%29%7D%2C%7Bx%2Cn%7D%29

Why can't i get maple to do it?

Best regards

Emil

### Accessing 2-variable answers from a list of varyin...

November 07 2015
1 1

I am using solve() to give me a two variable solutions (e.g. a = 3, b = 5). Very often, I have 2 solutions, so the output will be something like {a = .8025072621, b = -.8025072621}, {a = 1.326426441, b = 1.326426441}. I store this output in a matrix called Answers, so that looks like:

Later when I want to access these answers, I'll do Answers[1][1] to get the first a, and Answers[1][2] to get the first b. Overwhelmingly this all works fine, but occassionaly Answers only has one set of solutions, so Answers[1][1] becomes meaningless, for example, if solve() returned {a = 3, b = 4}, then Answers[1] just returns a, and Answers[2] returns b, but Answers[1][1] gives an error. As I cannot predict when solve() will give me one solutions as opposed to 2, how can I write code to reliably access the first solution for use later?

### How can i solve this equation?...

November 04 2015
1 11

hi all

how can i solve this program?

restart;
I5:=evalf(int((x^2)/((x^4-2*x0*x^2+x0^2+1)^(3/2)),x=0..infinity)):
I6:=evalf((1/2)*int(1/(x^4-2*x0*x^2+x0^2+1)^(1/2),x=0..infinity)):
A:=f-evalf((-4/Pi)*((x0*I6-I5)/(x0*I5+I6)^(1/3))):
B:=solve(A,x0);

### Error when executing procedure...

November 04 2015
1 2

Hello,

I'm writing a code and I seem to have an issue when trying to implement a procedure. Here is the code:

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 (1)
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Any help would be greatly appreciated.

Gambia Man

### Solving nonlinear equations...

November 03 2015
0 8

Hi

I need amount of P.

### How to solve system in that way?...

November 03 2015
0 6

Is there a command in Maple that directly divides one equation by another and produce the result as one equation directly? I wanted to verify the text book, where it says

x^2-y^2 = a*z^2   ----- (1)
x-y          = a*z       ------(2)
dividing (1) by (2) gives

x+y = z  ---(3)

So I typed this in Maple:

restart;
eq1:=x^2-y^2=a*z^2;
eq2:=x-y=a*z;

But now what to do? I can see the answer in book is correct by doing

solve( {eq1,eq2}, {x,y} );

And adding the solution given above, which shows it is z indeed.  But I'd like to get Maple to generate equation (3) above automatically.  Is this possible?

Maple 2015, windows 7

### Solving an equation...

October 31 2015
0 3

Hi everyone,

I'm trying to solve the following eqauation but Maple gives me the answer (( RootOf(mexp(-_Z*(m-1))*d^2-theta+_Z*theta-theta*c*t__kj) ))

The equation is:

solve(mexp(-(m-1)*t__ij)*d^2-theta+theta*t__ij-theta*(sum(t__kj, k = 1 .. c))-m*eta*(diff((1-1/exp(t))^m, t)) = 0, t__ij);

What is the meaning rootOF? Is there any explicit solution to that equation??

### Error, (in Engine:-Dispatch) invalid subscript sel...

October 31 2015
1 4

Hi everyone,

I'm trying to solve the following equation and unfortunately I get this error ( Error, (in Engine:-Dispatch) invalid subscript selector ) each time I try. Could you please help me??

I will be thankful for your great help.

solve(m*exp(-(m-1)*tij)*d2-θ+θ*tij-θ*(Σ(tkj, k = 1 .. c))-m*η*(1-exp(-tij))(m-1) = 0, tij)

### Error in the solve command...

October 27 2015
1 16

hi.please see attached file below and help me

Error, (in solve) cannot solve expressions with diff(diff(diff(f4(x), x), x), x) for diff(diff(f4(x), x), x)

thanks..error.mw

### Analytic solution of dsolve...

October 20 2015
0 1

Dear Collegues

I have a system of odes as follows

restart:
#gama1:=0.2:

#rhop:=5180:
#rhobf:=998.2:
#a[mu1]:=39.11:
#b[mu1]:=533.9:
#a[k1]:=7.47:
#b[k1]:=0:

Teq := N_bt*T(eta)^2*(exp(-(T(eta)-1)/(N_bt*(1+gama1)*(1+gama1*T(eta)))))^2*(diff(T(eta), eta, eta))*gama1^2*b[k1]+N_bt*T(eta)^2*exp(-(T(eta)-1)/(N_bt*(1+gama1)*(1+gama1*T(eta))))*(diff(T(eta), eta, eta))*gama1^2*a[k1]+2*N_bt*T(eta)*(exp(-(T(eta)-1)/(N_bt*(1+gama1)*(1+gama1*T(eta)))))^2*(diff(T(eta), eta, eta))*gama1*b[k1]+N_bt*T(eta)^2*(diff(T(eta), eta, eta))*gama1^2;

UEQ:=(a[mu1]*(-(diff(T(eta), eta))/(N_bt*(1+gama1)*(1+gama1*T(eta)))+(T(eta)-1)*gama1*(diff(T(eta), eta))/(N_bt*(1+gama1)*(1+gama1*T(eta))^2))*exp(-(T(eta)-1)/(N_bt*(1+gama1)*(1+gama1*T(eta))))+2*b[mu1]*(exp(-(T(eta)-1)/(N_bt*(1+gama1)*(1+gama1*T(eta)))))^2*(-(diff(T(eta), eta))/(N_bt*(1+gama1)*(1+gama1*T(eta)))+(T(eta)-1)*gama1*(diff(T(eta), eta))/(N_bt*(1+gama1)*(1+gama1*T(eta))^2)))*(diff(u(eta), eta))+(1+a[mu1]*exp(-(T(eta)-1)/(N_bt*(1+gama1)*(1+gama1*T(eta))))+b[mu1]*(exp(-(T(eta)-1)/(N_bt*(1+gama1)*(1+gama1*T(eta)))))^2)*(diff(u(eta), eta, eta))+1-exp(-(T(eta)-1)/(N_bt*(1+gama1)*(1+gama1*T(eta))))+exp(-(T(eta)-1)/(N_bt*(1+gama1)*(1+gama1*T(eta))))*rhop/rhobf;

I want to solve them with the following boundary conditions

T(0)=0, T(1)=1

u(0)=L*D(u)(0), D(u)(1)=0

However I tried, I cannot find the solution in a closed form. I want to know that is there a closed form solution for the above odes?

Thank you

Amir

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