Question

x-7√x-18=0 срочно надо​

Answer 1

Ответ:

81

Объяснение:

$1)x-7\sqrt{x}-18=0<=>49x=324-36x+x^2\\x^2-85x+324<=>(x-\frac{85}{2} )^2=\frac{5929}{4} =>x=4;x=81\\x=4=>4-7\sqrt{4}-18=0=>-28\neq  0\\x=81=>81-7\sqrt{81}-18=>0=0\\ x=81\\2)x-7\sqrt{x}-18=0<=>x+2\sqrt{x} -9\sqrt{x} -18=9<=>\\<=>\sqrt{x} (\sqrt{x} +2)-9(\sqrt{x}+2 )=0<=>(\sqrt{x}+2 )(\sqrt{x} -9)=0=>\\=>(\sqrt{x} -9)=0=>x=81$