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(z9)5⋅(z4)8(z4)4⋅(z4)15=7. equation

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Numerical solution:

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The solution

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z9*5*z4*8*z4*4*z4*15 = 7
$$15 z_{4} \cdot 4 z_{4} \cdot 8 z_{4} \cdot 5 z_{9} = 7$$
Detail solution
Given the linear equation:
(z9)*5*(z4)*8*(z4)*4*(z4)*15 = 7

Expand brackets in the left part
z9*5z4*8z4*4z4*15 = 7

Divide both parts of the equation by 2400*z4^3
z9 = 7 / (2400*z4^3)

We get the answer: z9 = 7/(2400*z4^3)
The solution of the parametric equation
Given the equation with a parameter:
$$2400 z_{4}^{3} z_{9} = 7$$
Коэффициент при z9 равен
$$2400 z_{4}^{3}$$
then possible cases for z4 :
$$z_{4} < 0$$
$$z_{4} = 0$$
Consider all cases in more detail:
With
$$z_{4} < 0$$
the equation
$$- 2400 z_{9} - 7 = 0$$
its solution
$$z_{9} = - \frac{7}{2400}$$
With
$$z_{4} = 0$$
the equation
$$-7 = 0$$
its solution
no solutions
The graph
Rapid solution [src]
        /            3                       2               \               3                       2               
        |        7*im (z4)               7*re (z4)*im(z4)    |           7*re (z4)               7*im (z4)*re(z4)    
z91 = I*|------------------------- - ------------------------| + ------------------------- - ------------------------
        |                        3                          3|                           3                          3
        |     /  2         2    \        /  2         2    \ |        /  2         2    \        /  2         2    \ 
        \2400*\im (z4) + re (z4)/    800*\im (z4) + re (z4)/ /   2400*\im (z4) + re (z4)/    800*\im (z4) + re (z4)/ 
$$z_{91} = i \left(- \frac{7 \left(\operatorname{re}{\left(z_{4}\right)}\right)^{2} \operatorname{im}{\left(z_{4}\right)}}{800 \left(\left(\operatorname{re}{\left(z_{4}\right)}\right)^{2} + \left(\operatorname{im}{\left(z_{4}\right)}\right)^{2}\right)^{3}} + \frac{7 \left(\operatorname{im}{\left(z_{4}\right)}\right)^{3}}{2400 \left(\left(\operatorname{re}{\left(z_{4}\right)}\right)^{2} + \left(\operatorname{im}{\left(z_{4}\right)}\right)^{2}\right)^{3}}\right) + \frac{7 \left(\operatorname{re}{\left(z_{4}\right)}\right)^{3}}{2400 \left(\left(\operatorname{re}{\left(z_{4}\right)}\right)^{2} + \left(\operatorname{im}{\left(z_{4}\right)}\right)^{2}\right)^{3}} - \frac{7 \operatorname{re}{\left(z_{4}\right)} \left(\operatorname{im}{\left(z_{4}\right)}\right)^{2}}{800 \left(\left(\operatorname{re}{\left(z_{4}\right)}\right)^{2} + \left(\operatorname{im}{\left(z_{4}\right)}\right)^{2}\right)^{3}}$$
z91 = i*(-7*re(z4)^2*im(z4)/(800*(re(z4)^2 + im(z4)^2)^3) + 7*im(z4)^3/(2400*(re(z4)^2 + im(z4)^2)^3)) + 7*re(z4)^3/(2400*(re(z4)^2 + im(z4)^2)^3) - 7*re(z4)*im(z4)^2/(800*(re(z4)^2 + im(z4)^2)^3)
Sum and product of roots [src]
sum
  /            3                       2               \               3                       2               
  |        7*im (z4)               7*re (z4)*im(z4)    |           7*re (z4)               7*im (z4)*re(z4)    
I*|------------------------- - ------------------------| + ------------------------- - ------------------------
  |                        3                          3|                           3                          3
  |     /  2         2    \        /  2         2    \ |        /  2         2    \        /  2         2    \ 
  \2400*\im (z4) + re (z4)/    800*\im (z4) + re (z4)/ /   2400*\im (z4) + re (z4)/    800*\im (z4) + re (z4)/ 
$$i \left(- \frac{7 \left(\operatorname{re}{\left(z_{4}\right)}\right)^{2} \operatorname{im}{\left(z_{4}\right)}}{800 \left(\left(\operatorname{re}{\left(z_{4}\right)}\right)^{2} + \left(\operatorname{im}{\left(z_{4}\right)}\right)^{2}\right)^{3}} + \frac{7 \left(\operatorname{im}{\left(z_{4}\right)}\right)^{3}}{2400 \left(\left(\operatorname{re}{\left(z_{4}\right)}\right)^{2} + \left(\operatorname{im}{\left(z_{4}\right)}\right)^{2}\right)^{3}}\right) + \frac{7 \left(\operatorname{re}{\left(z_{4}\right)}\right)^{3}}{2400 \left(\left(\operatorname{re}{\left(z_{4}\right)}\right)^{2} + \left(\operatorname{im}{\left(z_{4}\right)}\right)^{2}\right)^{3}} - \frac{7 \operatorname{re}{\left(z_{4}\right)} \left(\operatorname{im}{\left(z_{4}\right)}\right)^{2}}{800 \left(\left(\operatorname{re}{\left(z_{4}\right)}\right)^{2} + \left(\operatorname{im}{\left(z_{4}\right)}\right)^{2}\right)^{3}}$$
=
  /            3                       2               \               3                       2               
  |        7*im (z4)               7*re (z4)*im(z4)    |           7*re (z4)               7*im (z4)*re(z4)    
I*|------------------------- - ------------------------| + ------------------------- - ------------------------
  |                        3                          3|                           3                          3
  |     /  2         2    \        /  2         2    \ |        /  2         2    \        /  2         2    \ 
  \2400*\im (z4) + re (z4)/    800*\im (z4) + re (z4)/ /   2400*\im (z4) + re (z4)/    800*\im (z4) + re (z4)/ 
$$i \left(- \frac{7 \left(\operatorname{re}{\left(z_{4}\right)}\right)^{2} \operatorname{im}{\left(z_{4}\right)}}{800 \left(\left(\operatorname{re}{\left(z_{4}\right)}\right)^{2} + \left(\operatorname{im}{\left(z_{4}\right)}\right)^{2}\right)^{3}} + \frac{7 \left(\operatorname{im}{\left(z_{4}\right)}\right)^{3}}{2400 \left(\left(\operatorname{re}{\left(z_{4}\right)}\right)^{2} + \left(\operatorname{im}{\left(z_{4}\right)}\right)^{2}\right)^{3}}\right) + \frac{7 \left(\operatorname{re}{\left(z_{4}\right)}\right)^{3}}{2400 \left(\left(\operatorname{re}{\left(z_{4}\right)}\right)^{2} + \left(\operatorname{im}{\left(z_{4}\right)}\right)^{2}\right)^{3}} - \frac{7 \operatorname{re}{\left(z_{4}\right)} \left(\operatorname{im}{\left(z_{4}\right)}\right)^{2}}{800 \left(\left(\operatorname{re}{\left(z_{4}\right)}\right)^{2} + \left(\operatorname{im}{\left(z_{4}\right)}\right)^{2}\right)^{3}}$$
product
  /            3                       2               \               3                       2               
  |        7*im (z4)               7*re (z4)*im(z4)    |           7*re (z4)               7*im (z4)*re(z4)    
I*|------------------------- - ------------------------| + ------------------------- - ------------------------
  |                        3                          3|                           3                          3
  |     /  2         2    \        /  2         2    \ |        /  2         2    \        /  2         2    \ 
  \2400*\im (z4) + re (z4)/    800*\im (z4) + re (z4)/ /   2400*\im (z4) + re (z4)/    800*\im (z4) + re (z4)/ 
$$i \left(- \frac{7 \left(\operatorname{re}{\left(z_{4}\right)}\right)^{2} \operatorname{im}{\left(z_{4}\right)}}{800 \left(\left(\operatorname{re}{\left(z_{4}\right)}\right)^{2} + \left(\operatorname{im}{\left(z_{4}\right)}\right)^{2}\right)^{3}} + \frac{7 \left(\operatorname{im}{\left(z_{4}\right)}\right)^{3}}{2400 \left(\left(\operatorname{re}{\left(z_{4}\right)}\right)^{2} + \left(\operatorname{im}{\left(z_{4}\right)}\right)^{2}\right)^{3}}\right) + \frac{7 \left(\operatorname{re}{\left(z_{4}\right)}\right)^{3}}{2400 \left(\left(\operatorname{re}{\left(z_{4}\right)}\right)^{2} + \left(\operatorname{im}{\left(z_{4}\right)}\right)^{2}\right)^{3}} - \frac{7 \operatorname{re}{\left(z_{4}\right)} \left(\operatorname{im}{\left(z_{4}\right)}\right)^{2}}{800 \left(\left(\operatorname{re}{\left(z_{4}\right)}\right)^{2} + \left(\operatorname{im}{\left(z_{4}\right)}\right)^{2}\right)^{3}}$$
=
  /  3           2                /  2           2    \       \
7*\re (z4) - 3*im (z4)*re(z4) + I*\im (z4) - 3*re (z4)/*im(z4)/
---------------------------------------------------------------
                                           3                   
                        /  2         2    \                    
                   2400*\im (z4) + re (z4)/                    
$$\frac{7 \left(i \left(- 3 \left(\operatorname{re}{\left(z_{4}\right)}\right)^{2} + \left(\operatorname{im}{\left(z_{4}\right)}\right)^{2}\right) \operatorname{im}{\left(z_{4}\right)} + \left(\operatorname{re}{\left(z_{4}\right)}\right)^{3} - 3 \operatorname{re}{\left(z_{4}\right)} \left(\operatorname{im}{\left(z_{4}\right)}\right)^{2}\right)}{2400 \left(\left(\operatorname{re}{\left(z_{4}\right)}\right)^{2} + \left(\operatorname{im}{\left(z_{4}\right)}\right)^{2}\right)^{3}}$$
7*(re(z4)^3 - 3*im(z4)^2*re(z4) + i*(im(z4)^2 - 3*re(z4)^2)*im(z4))/(2400*(im(z4)^2 + re(z4)^2)^3)