Let the function
f(x)=3x2−4x+8log1+x be defined on the interval [0, 1]. The even extension of f(x) of the interval [-1, 1] is
3x2−4x+8log1+x
3x2+4x−8log1+x
3x2−4x−8log1+x
f(x)=−f(x) x∈[0,1]
−f(−x) x∈[−1,0]
f(x)=3x2−4x+8log1+xx∈[0,1]
f(x)=3x2+4x+8log1+xx∈[−1,0]
∴f(x)=3x2−4x+8log1+xx∈[−1,1]