Question 1119850
{{{(1/x)^2+15(1/x)+56=0}}}


{{{let}}}{{{v=1/x}}};


{{{v^2+15v+56=0}}}


{{{v=(-15+- sqrt(15^2-4*56))/2}}}


{{{v=(-15+- sqrt(1))/2}}}


{{{v=(-15+- 1)/2}}}


{{{system(v=-7,or,v=-8)}}}

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Now backsubstitute v for each of these and solve for x.

{{{system(1/x=-7, or, 1/x=-8)}}};


{{{system(highlight(x=-1/7),or,highlight(x=-1/8))}}}

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You could also check for possible factorization at the beginning:

{{{(1/x)^2+15(1/x)+56=0}}}
{{{((1/x)+7)((1/x)+8)=0}}}------and solve for {{{1/x}}} from here.