solve for x:

x + sqrt(x) - 12 = 0

Question

solve for x:

x + sqrt(x) - 12 = 0

anonymous · Answer

x= 3is you answer.

anonymous · Answer

firstly 
let x = [y ^{2}\]

anonymous · Answer

and then solve the new form of equation :
$$y ^{2}+y-12 = 0$$
and find the answers for y
after that omit the unsuitable answers for x those which are negative I mean.

anonymous · Answer

was it useful ?

anonymous · Answer

$$y ^{2}+y -12 = 0 $$
=>
$$(y+4)(y-3)= 0$$
so y can be 3 or -4.but x cannot be sqrt(-4) so x is sqrt(3).

lgbasallote · Answer

actually @mas_gh90 ... if y = 3 and y = -4...then sq x = 3 and sq x = -4

so x = 9 and x =16

anonymous · Answer

that doesn't make sense, can we just make  x = y^2?

lgbasallote · Answer

yes...x = y^2..so y = sqrt of x...since the final answers involve y and not y^2 you substitute back to sqrt x then square it to get x. Do you get it? :D

anonymous · Answer

you're completely right dear lgbasallote,sorry for my foolish mistake.

anonymous · Answer

alright i get it thank you both!

anonymous · Answer

Don't mention it =)

anonymous · Answer

x +√x - 12 = 0
√x  = 12 -x
->x = ( 12 - x)²
 x = 144 - 24x + x²
 x² - 25x + 144 = 0
=> x = 16, x = 9