Laurenso

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0 years, 273 days

MaplePrimes Activity


These are questions asked by Laurenso

I make a function 
myf := (a, b, c) -> [a*x^2 + b*x + c = 0, solve(a*x^2 + b*x + c = 0, {x})];

I tried 

myf(1, 2, -3);

and get

[x^2 + 2*x - 3 = 0, {x = 1}, {x = -3}]

With list mylist := [[1, 2, -3], [3, 2, -1]];

How can I map myf  onto mylist?

I tried 

myf := (a, b, c) -> [a*x^2 + b*x + c = 0, solve(a*x^2 + b*x + c = 0, {x})];
mylist := [[1, 2, -3], [3, 2, -1]];
map(myf, mylist);

I can not get the result. 

I am trying to print all the equations of sphere in the form (x-a)^2 + (y-b)^2 + (z-c)^2-10^2=0?
my code
restart;
n := 0;
for a to 5 do
    for b to 5 do for c to 5 do mysphere := (x - a)^2 + (y - b)^2 + (z - c)^2 - 10^2 = 0;
if a*b*c <> 0 and igcd(a, b, c) = 1 then n := n + 1; L[n] := [a, b, c];
end if;
end do;
end do;
end do;
L := convert(L, list);
map(mysphere, L);
print(mysphere);


I don't get the correct results. How can get correct results?

list:= [[-12, 3, 5], [-11, -2, 5], [-11, -1, 2], [-11, -1, 8], [-11, 0, 
        1], [-11, 0, 9], [-11, 3, 0], [-11, 3, 10], [-11, 6, 1], [-11, 6, 
        9], [-11, 7, 2], [-11, 7, 8], [-11, 8, 5], [-4, -9, 5], [-4, 
        3, -7], [-4, 3, 17], [-4, 15, 5], [-3, -9, 2], [-3, -9, 8], [-3, 
        0, -7], [-3, 0, 17], [-3, 6, -7], [-3, 6, 17], [-3, 15, 2], [-3, 15,
        8], [-2, -9, 1], [-2, -9, 9], [-2, -1, -7], [-2, -1, 17], [-2, 
        7, -7], [-2, 7, 17], [-2, 15, 1], [-2, 15, 9], [1, -10, 5], [1, -9, 
        0], [1, -9, 10], [1, -2, -7], [1, -2, 17], [1, 3, -8], [1, 3, 
        18], [1, 8, -7], [1, 8, 17], [1, 15, 0], [1, 15, 10], [1, 16, 
        5], [4, -9, 1], [4, -9, 9], [4, -1, -7], [4, -1, 17], [4, 
        7, -7], [4, 7, 17], [4, 15, 1], [4, 15, 9], [5, -9, 2], [5, -9, 
        8], [5, 0, -7], [5, 0, 17], [5, 6, -7], [5, 6, 17], [5, 15, 2], [5, 
        15, 8], [6, -9, 5], [6, 3, -7], [6, 3, 17], [6, 15, 5], [13, -2, 
        5], [13, -1, 2], [13, -1, 8], [13, 0, 1], [13, 0, 9], [13, 3, 
        0], [13, 3, 10], [13, 6, 1], [13, 6, 9], [13, 7, 2], [13, 7, 
        8], [13, 8, 5], [14, 3, 5]];
These points are lies on the sphere (x - 1)^2 + (y - 3)^2 + (z - 5)^2 = 13^2. How to write the equation of the planes tangent to the sphere at the points in the list? This is some equations.
I tried

restart;
with(geom3d);
L := [[-12, 3, 5], [-11, -2, 5], [-11, -1, 2], [-11, -1, 8], [-11, 0, 1], [-11, 0, 9], [-11, 3, 0], [-11, 3, 10], [-11, 6, 1], [-11, 6, 9], [-11, 7, 2], [-11, 7, 8], [-11, 8, 5], [-4, -9, 5], [-4, 3, -7], [-4, 3, 17], [-4, 15, 5], [-3, -9, 2], [-3, -9, 8], [-3, 0, -7], [-3, 0, 17], [-3, 6, -7], [-3, 6, 17], [-3, 15, 2], [-3, 15, 8], [-2, -9, 1], [-2, -9, 9], [-2, -1, -7], [-2, -1, 17], [-2, 7, -7], [-2, 7, 17], [-2, 15, 1], [-2, 15, 9], [1, -10, 5], [1, -9, 0], [1, -9, 10], [1, -2, -7], [1, -2, 17], [1, 3, -8], [1, 3, 18], [1, 8, -7], [1, 8, 17], [1, 15, 0], [1, 15, 10], [1, 16, 5], [4, -9, 1], [4, -9, 9], [4, -1, -7], [4, -1, 17], [4, 7, -7], [4, 7, 17], [4, 15, 1], [4, 15, 9], [5, -9, 2], [5, -9, 8], [5, 0, -7], [5, 0, 17], [5, 6, -7], [5, 6, 17], [5, 15, 2], [5, 15, 8], [6, -9, 5], [6, 3, -7], [6, 3, 17], [6, 15, 5], [13, -2, 5], [13, -1, 2], [13, -1, 8], [13, 0, 1], [13, 0, 9], [13, 3, 0], [13, 3, 10], [13, 6, 1], [13, 6, 9], [13, 7, 2], [13, 7, 8], [13, 8, 5], [14, 3, 5]];
eqS := Equation(sphere(S, (x - 1)^2 + (y - 3)^2 + (z - 5)^2 - 169 = 0, [x, y, z], 'centername' = T));
k := [seq](sort(Equation(TangentPlane(P, S, point(A, pt[])), [x, y, z])), pt in L);
seq([L[i], k[i]], i = 1 .. nops(L));


I get

With each equation has the form a*x  + b*y + c*x + d=0, how can I get in the form igcd(a,b,c,d) = 1 and a >0. If a = 0, then b>0; If b = 0, then c>0. 

PS. I use this expr := sort(primpart(3*x + 6*y + 12));
expr*signum(lcoeff(expr)) = 0;

But I do not know use it in the seq k

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