Question 1135089
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Introduce new variable  u = {{{sqrt(x)}}}.  


Then our equation becomes


    u^2 -3u - 10 = 0.


Factor left side


    (u-5)*(u+2) = 0.


The solutions are  u= 5  and  u= -2.


a)  If u = 5,  then  {{{sqrt(x)}}} = 5,  hence x = 25.


b)  if u = -2, we reject  the possibility for  {{{sqrt(x)}}} to be negative, as your teachers and your textbooks teach you at the school.


<U>ANSWER</U>.  x= 25.
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