Question

решить уравнение 2((5-x^2) ^ (1/2)) =x-1

Answer 1

Объяснение:

$2*(5-x^2)^\frac{1}{2}=x-1$

ОДЗ:

$\left \{ {{5-x^2\geq 0\ *(-1)} \atop {x-1\geq0 }} \right. \ \ \ \ \left \{ {{x^2-5\leq 0} \atop {x\geq 1}} \right. \ \ \ \ \left \{ {{(x+\sqrt{5})*(x-\sqrt{5})\leq 0 } \atop {x\geq 1}} \right. \ \ \ \ \left \{ {{x\in[-\sqrt{5};\sqrt{5}] } \atop {x\in[1;+\infty)}} \right. \ \ \ \Rightarrow\\ \ x\in[1;\sqrt{5}]\ \ \ \ \ \ x\in[1;\approx2,236].$

$(2*\sqrt{5-x^2})^2=(x-1)^2\\4*(5-x^2)=x^2-2x+1\\20-4x^2=x^2-2x+1\\5x^2-2x-19=0\\D=384\ \ \ \ \sqrt{D}=8\sqrt{6} \\x_1=0,2-0,8\sqrt{6}\approx-1,76\notin.\\x _2=0,2+0,8\sqrt{6}\approx2,16\in.$

Ответ: x=0,2+0,8√6.