# Question:fsolve when the number of variables is greater than 9

## Question:fsolve when the number of variables is greater than 9

When I work with the fsolve and the number of variables is greater than 9, I have to use the op very carefully, because the order of the variables changes. The same thing happens when working with dsolve(numeric), which is especially inconvenient. For example, the RootFinding [Isolate]  works fine.
I ran into this a very long time ago and I have examples with 15 variables. It is completely unclear why such was done.
How to work with it or how to avoid it?
Example of the same solution using  fsolve and RootFinding [Isolate]

```restart:
CD1 := -.5; CD2 := 2; CD3 := 1.;
g1 := 5.; g2 := 3.; g3 := 2.;
cg1 := 0.; cg2 := 3.7; cg3 := 1;
cd1 := 7.5; cd2 := 0; cd3 := 0;
L1 := .72; L2 := 8.6; L3 := 5.5; L4 := 1.25; L5 := 3.102; L6 := 5.1; L7 := 7.;
f1 := (CD1-x4)^2+(CD2-x5)^2+(CD3-x6)^2-L1^2;
f2 := x1-5;
f3 := x5-1.45;
f4 := (g1-x1)^2+(g2-x2)^2+(g3-x3)^2-L3^2;
f5 := (x7-x1)^2+(x8-x2)^2+(x9-x3)^2-L2^2;
f6 := (cg1-x7)^2+(cg2-x8)^2-(cg3-x9)^2-L4^2;
f7 := x7+x8-1.2*cg2;
f8 := (x4-x7)^2+(x5-x8)^2+(x6-x9)^2-L5^2;
f9 := (cd1-x10)^2+(cd2-x11)^2+(cd3-x12)^2-L6^2;
f10 := (x1-x10)^2+(x2-x11)^2+(x3-x12)^2-L7^2;
f11 := x11-.1*x12;
f12 := x1-x2-x3-x4+x5+x6+x7+x8+x9+x10+x11-x12;
fsolve({f1, f2, f3, f4, f5, f6, f7, f8, f9, f10, f11, f12});
RootFinding[Isolate]([f1, f2, f3, f4, f5, f6, f7, f8, f9, f10, f11, f12], [x1, x2, x3, x4, x5, x6, x7, x8, x9, x10, x11, x12])[4];
{x1 = 5.000000000, x10 = 6.265979021, x11 = 0.4923895285,
x12 = 4.923895285, x2 = 7.363909611, x3 = 5.347580157,
x4 = -0.4802494112, x5 = 1.450000000, x6 = 0.5357695462,
x7 = 2.014012007, x8 = 2.425987993, x9 = -1.029002454}
[x1 = 5., x2 = 7.363909611, x3 = 5.347580157, x4 = -0.4802494112,
x5 = 1.450000000, x6 = 0.5357695462, x7 = 2.014012007,
x8 = 2.425987993, x9 = -1.029002454, x10 = 6.265979021,
x11 = 0.4923895285, x12 = 4.923895285]
```

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