Question

If $S={\int }_1^{\infty }{x}^{-3}dx$, then $S$ has the value

• A. $-1/3$
• B. $1/4$
• C. $1/2$
• D. $1$

Answer 1

The correct option is C $1/2$

$S={\int }_1^{\infty }{x}^{-3}dx={\left[\frac{x^{-2}}{-2}\right]}_1^{\infty }=-\frac{1}{2}[0-1]=\frac{1}{2}$