f:R→[−2,2] twice differentiable
(f(0))2+(f′(0))2=85
Which of (1) - (4) is/are TRUE?
f:R→[−2,2],(f(0))2+(f′(0))2=85
∣f(0)∣≤2⇒(f′(0))2=85−(f(0))2≥81
⇒∣f′(0)∣≥9=0
(1) local monotonicity
(2) MVT on [−4,0]
(3) limit at ∞;(4) h=f2+f′2
f′(0)=0, f′ continuous⇒f′ keeps sign near 0
⇒f one-one on some (r,s)⇒(1) TRUE
MVT on [−4,0]: f(0)−f(−4)=4f′(x0)
∣f(0)−f(−4)∣≤4⇒∣f′(x0)∣≤1⇒(2) TRUE
limx→∞f(x)=1 is not forced⇒(3) FALSE
h(x)=f(x)2+f′(x)2,h(0)=85
h′(x)=2f′(x)(f(x)+f′′(x))
c1∈(−4,0), c2∈(0,4): ∣f′(ci)∣≤1⇒h(ci)≤5
max[c1,c2]h≥h(0)=85>5⇒interior max at α
h′(α)=0, f′(α)2≥85−4=81=0⇒f(α)+f′′(α)=0
(1), (2), (4) are TRUE