Question

1) x+3√x-18=0
2) (x+1)^4-2(x+1)^2-3=0

Answer 1

Ответ: x=36

1) x+3√x-18=0

3√x-18= - x

9(x-18)=x^2

9x-162=x^2

9x-162-x^2=0

-x^2+9x-162=0

x= -(-9)±$\sqrt{(-9)^{2}-4*1*162}$ \ 2*1

x1= $\frac{9+\sqrt{81-648} }{2}$

x2= $\frac{9+\sqrt{81+648} }{2}$

x1= $\frac{9+\sqrt{-567} }{2}$=6

x2=$\frac{9-\sqrt{-567} }{2}$=-3

$\sqrt{x} =6\\x=36$

$\sqrt{x} =-3$=∉