Question

急,快来帮我,本人数学不好

Answer 1

20.由f(0)=5,f(-1)=4,f(2)=1得 f(0)=c=5;a-b+c=4;4a+2b+c=1

得到a=-1b=0c=5 =>f(x)=-x2 + 5

(2)-x2+5>0 => x2 负根5