Question

корень(корень(x-1) + корень(x+2)) = 3

Answer 1

$ODZ: left { {{x-1>0} atop {x+2>0}} right. => left { {{x>1} atop {x>-2}} right. =>x>1 \ sqrt{ sqrt{x-1} + sqrt{x+2} }^2=3^2 \ sqrt{x-1} + sqrt{x+2} =9 \ sqrt{x-1}^2=(9-sqrt{x+2})^2 \ x-1=81-18sqrt{x+2}+x+2 \ 18sqrt{x+2}=84 \ (9sqrt{x+2})^2=42^2 \ 81(x+2)=1764 \ x= frac{1764-2*81}{81} \ x= frac{1602}{81}= 19 frac{63}{81}=19 frac{31}{27}$