For the ϵ\epsilonϵ-δ\deltaδ proof of limx→0x2sin(1/x)=0\lim_{x \to 0} x^2 \sin(1/x) = 0limx→0x2sin(1/x)=0, which bound is used?
∣x2sin(1/x)∣≤x2|x^2 \sin(1/x)| \leq x^2∣x2sin(1/x)∣≤x2 for all x≠0x \neq 0x=0
∣x2sin(1/x)∣≤∣x∣|x^2 \sin(1/x)| \leq |x|∣x2sin(1/x)∣≤∣x∣ for all xxx
∣x2sin(1/x)∣≤∣sin(1/x)∣|x^2 \sin(1/x)| \leq |\sin(1/x)|∣x2sin(1/x)∣≤∣sin(1/x)∣ for all xxx
∣x2sin(1/x)∣≤1/x2|x^2 \sin(1/x)| \leq 1/x^2∣x2sin(1/x)∣≤1/x2 for x>0x>0x>0