已知函数f(x)=\left\{\begin{array}{l}{x+\frac{1}{x},x>0,}\\{{x}^{3}+3,x≤0,}\end{array}\right.已知函数f(x)=\left\{\begin{array}{l}{x+\frac{1}{x},x＞0,}\\{{x}^{3}+3,x≤0,}\end{array}\right.则函数y=f(2{x}^{2}+x)-a(a＞2)零点个

Question

已知函数f(x)=\left\{ \begin{array}{l}{x+\frac{1}{x},x>0,} \\ {{x}^{3}+3,x≤0,} \end{array} \right.
已知函数f(x)=\left\{ \begin{array}{l}{x+\frac{1}{x},x＞0,} \\ {{x}^{3}+3,x≤0,} \end{array} \right.则函数y=f(2{x}^{2}+x)-a(a＞2)零点个数不可能是\;A.3\;B.4\;C.5\;D.6

Answer 1

零点的个数不可能是,BCD.把2{x}^{2}+x看成整体t,t的范围是[-\frac{1}{8},+\infty],代入f（t）画图即可