证明:当t∈R时,有t^4

证明:当t∈R时,有t^4: 证明: t^4-t+1/2 =(t^4-t^2+1/4)+(t^2-t+1/4) =(t^2-1/2)^2+(t-1/2)^2 >0 ∴t^4-t+1/2>0恒成立.