f′(x)=ef(x)−g(x)g′(x),∀x∈R
f(1)=1,g(2)=1
Compare f(2), g(1) with 1−loge2
f′(x)e−f(x)=g′(x)e−g(x)
−dxd(e−f(x))=−dxd(e−g(x))
⇒dxd(e−f(x)−e−g(x))=0
⇒e−f(x)−e−g(x)=C (constant)
x=1: C=e−1−e−g(1)
x=2: C=e−f(2)−e−1
e−1−e−g(1)=e−f(2)−e−1
⇒e−f(2)+e−g(1)=2e−1
e−g(1)>0⇒e−f(2)<2e−1
⇒−f(2)<ln2−1⇒f(2)>1−loge2
⇒(2) true, (1) false
e−f(2)>0⇒e−g(1)<2e−1
⇒g(1)>1−loge2⇒(3) true, (4) false
True statements: (2) and (3)