Question 1170876
Coordinates  ....|....  Quadrant
{{{P}}}({{{x}}} , {{{-5/7}}}) ....|.... {{{ IV}}}


{{{x^2 + (-5/7)^2 = 1^2}}}

{{{x^2 + 25/49 = 1 }}}

{{{x^2   = 1 -25/49}}}

{{{x^2   = 24/49}}}

{{{x= sqrt(24/49)}}}.........The sign is  "+" (plus) at sqrt operator, because the point is in Quadrant IV

{{{x=(2sqrt(6))/7 }}}->exact solution

{{{P}}}({{{(2sqrt(6))/7}}}, {{{-5/7}}})