Question 683656
Let the unknown number = {{{ n }}}
given:
{{{ n - 2*(1/n) = -7/5 }}}
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Multiply both sides by {{{ 5n }}}
{{{ 5n^2 - 10 = -7n }}}
{{{ 5n^2 + 7n - 10 = 0 }}}
Use the quadratic formula
{{{ n = (-b +- sqrt( b^2 - 4*a*c )) / (2*a) }}}
{{{ a = 5 }}}
{{{ b = 7 }}}
{{{ c = -10 }}}
{{{ n = (-7 +- sqrt( 7^2 - 4*5*(-10) )) / (2*5) }}}
{{{ n = (-7 +- sqrt( 49 + 200 )) / 10 }}}
{{{ n = (-7 +- sqrt( 249 )) / 10 }}}
The 2 answers are
{{{ n =  (-7 + sqrt( 249 )) / 10 }}}
{{{ n =  (-7 - sqrt( 249 )) / 10 }}}
I could have made a mistake. You might want
to get a 2nd opinion on this.