#### Answer

Prove that for every positive real number $B$, there exists a corresponding $\delta\gt0$ such that for all $x$ $$0\lt x\lt \delta\Rightarrow \frac{1}{x}\gt B$$

#### Work Step by Step

$$\lim_{x\to0^+}\frac{1}{x}=\infty$$
According to the formal definition, we need to prove that for every positive real number $B$, there exists a corresponding $\delta\gt0$ such that for all $x$ $$0\lt x\lt \delta\Rightarrow \frac{1}{x}\gt B$$
- Examine the inequality: $$\frac{1}{x}\gt B$$ $$x\lt\frac{1}{B}$$
- So if we set $\delta=\frac{1}{B}$, then $0\lt x\lt\frac{1}{B}$, we would for all $x$ have $\frac{1}{x}\gt B$, satisfying the requirements.
The proof has been completed.