The formula in this integral symbol is a probability density function with normal distribution, and its definite integral cannot be solved by finite addition, subtraction, multiplication and division of basic elementary functions, but for any probability density function, its definite integral from negative infinity to positive infinity is 1.

The probability density function of normal distribution is f (x) = e {[-(x-μ)? /2σ? ]/[√(2π)σ]}, where μ and σ can be arbitrary values, and μ=σ= 1 in this question.