题目若函数y={x2+2(x≤2)2x(x＞2)y=\left\{\begin{array}{l}{x^2}+2(x≤2)\\ 2x(x＞2)\end{array}\right.y={x2+2(x≤2)2x(x＞2),则当函数值y=8y=8y=8时,自变量xxx的值是（ ）A.±6\pm \sqrt{6}±6B.444C.±6\pm \sqrt{6}±6或444D.444或−6-\sqrt{6}−6知识点：函数值章节：未标注
