Question

Срочно!!!! помогите решить

Answer 1

$1) \;\;2 \sqrt{x^2+8}=2x+1 \;\;\mid\;(^2) \\ \\ 4(x^2+8)=4x^2+4x+1 \\ \\ 4x^2+32=4x^2+4x+1 \\ \\ -4x=-31 \\ \\ x= \frac{31}{4}=7 \frac{3}{4} \\ \\ \\ 2)\;\;2 \sqrt{5-x^2}=x-1\;\;\mid \;(^2) \\ \\ 4(5-x^2)=x^2-2x+1 \\ \\ 20-4x^2=x^2-2x+1 \\ \\ -5x^2+2x+19=0 \mid\;*(-1) \\ \\ 5x^2-2x+19=0 \\ \\ D=384; \sqrt{D}= \sqrt{384} \\ \\ x_1= \frac{2+8 \sqrt{6} }{10} = \frac{1+4 \sqrt{6} }{5} \\ x_2= \frac{2-8 \sqrt{6} }{10} = \frac{1-4 \sqrt{6} }{5} \\ \\ Po \;\; proverke \;\;\frac{1-4 \sqrt{6} }{5} \;\; ne \;\; podxodit ! \\ \\ \boxed{OTBET: \frac{1+4 \sqrt{6} }{5} }$