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Question: How to find the real solution where two curves intersect when solution has _Z?

Question:How to find the real solution where two curves intersect when solution has _Z?

ahmeng 40 Maple 2017
solve rootfinding rootof
November 29 2020
2

I have two functions, f(x) and g(x).

Based the plot, I can see that they intersect around x equals 0, 1, around 4.5 and 10.

So I tried to find the numerical solution by solving f(x) - g(x) for x assuming x is real.

I'm stuck here because the aswer involves RootOf and _Z and I don't know what to do next.

This is what I've tried so far:
 

``

``

"f(x):=18*log10(x)"

proc (x) options operator, arrow; 18*log10(x) end proc

 (1)

"g(x):=1/(2) x^(3)-8*x^(2)+(69/(2))^()*x-27"

proc (x) options operator, arrow; (1/2)*x^3-8*x^2+(69/2)*x-27 end proc

 (2)

plot([f(x), g(x)], x = -1 .. 11)

  

``

`assuming`([solve(f(x)-g(x), x)], [x::real])

exp(RootOf(-(exp(_Z))^3*ln(10)+16*(exp(_Z))^2*ln(10)-69*exp(_Z)*ln(10)+54*ln(10)+36*_Z))

 (3)

allvalues(exp(RootOf(-(exp(_Z))^3*ln(10)+16*(exp(_Z))^2*ln(10)-69*exp(_Z)*ln(10)+54*ln(10)+36*_Z)))

exp(RootOf(-(exp(_Z))^3*ln(10)+16*(exp(_Z))^2*ln(10)-69*exp(_Z)*ln(10)+54*ln(10)+36*_Z, 1.505446443)), exp(RootOf(-(exp(_Z))^3*ln(10)+16*(exp(_Z))^2*ln(10)-69*exp(_Z)*ln(10)+54*ln(10)+36*_Z, -3.291052648)), exp(RootOf(-(exp(_Z))^3*ln(10)+16*(exp(_Z))^2*ln(10)-69*exp(_Z)*ln(10)+54*ln(10)+36*_Z, 2.302585093)), 1

 (4)

``

``


 

Download intersect_curve.mw

 

I know there's an answer to this because I can get the expected answer from Wolfram Alpha (see here).

How can I accomplish this in Maple? 
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