Question 1121541
{{{log(5,x)+3/log(5,x)=7/2}}}


{{{Let}}} {{{v=log(5,x)}}}
Use that to make the substitution for {{{log(5,x)}}},
and you can write

{{{v+3/v=7/2}}} .

There is no "moving v underneath".  There is not yet any "{{{v^2}}}".


Solve this for v.   



Next steps may be, multiply left and right sides by lowest or simplest common denominator of {{{2v}}}.   (Basic fractionss skills).
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{{{2v(v+3/v)=2v(7/2)}}}

{{{2v^2+6=7v}}}

{{{2v^2-7v+6=0}}}----------maybe you can continue on your own from this.