Question 1134359
{{{ ( c*x + d ) /(  a / ((c*x) / d) ) = ( 2d )/ a }}}
{{{ ( c*x + d ) / (( a*d ) / ( c*x )) = (2d) / a }}}
{{{ (( c*x + d )*( c*x )) / ( a*d ) = ( 2d )/a }}}
{{{ ( c*x + d )*( c*x ) = ( a*d )*(2d/a ) }}}
{{{ c^2*x^2 + c*d*x = 2d^2 }}}
{{{ ( c^2 )*x^2 + ( c*d )*x - 2d^2 = 0 }}}
{{{ a*x^2 + b*x + c = 0 }}} use this form
{{{ a = c^2 }}}
{{{ b = c*d }}}
{{{ c = -2*d^2 }}}
{{{ x = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}} 
{{{ x = (-c*d +- sqrt( c^2d^2 - 4*c^2*2*(-2d^2) ))/(2*c^2) }}} 
{{{ x = (-c*d +- sqrt( (c*d)^2 + 8*(c*d)^2 ))/(2*c^2) }}} 
{{{ x = (-c*d +- sqrt( 9*(c*d)^2 ))/(2*c^2) }}} 
{{{ x = ( -c*d +- ( 3*c*d ) )/ ( 2*c^2 ) }}}
{{{ x = -d/(2*c) + (3/2)*( d/c ) }}}
{{{ x = ( d/c )*( (3/2) - (1/2) ) }}}
{{{ x = d/c }}}
and, the other root:
{{{ x = -(1/2)*(d/c) - (3/2)*( d/c) }}}
{{{ x = -2*( d/c) }}}
You can plug these results back into original equation to check
Definitely get another opinion if needed