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\chapter{Complex Numbers}
Complex numbers play important role in mathematics and in sciences. The use of complex numbers is indispensable in Physics.
Real Numbers: All numbers whose square is positive $(x^2?0)$ are known as real numbers.
Imaginary Numbers: Besides real numbers there are numbers whose square gives negative $(x^2<0)$ are called imaginary numbers.
For example, consider the following equations:
$x^2+1=0$,$x^2+4=0$,$x^2+5=0$,…
The equation $x^2+1=0$
Or has no solution among the real numbers. Thus we can not find a real number that can satisfy the above equation. Similarly, $x^2+4=0$,$x^2+5=0$ and so on.
To resolve this issue, Mathematicians introduced a new number denoted by a Greek letter of alphabet i(iota) such that $i=?(-1)$ which is called the imaginary unit. If we square both sides of Eq. (1), we have $i^2=-1$ a result that can not be obtained with real numbers. Using this new new number iota we can also define the imaginary numbers as: `` All numbers having iota in their factorization are called imaginary numbers.'' A simple consequences of the definition of iota is that all powers of iota may be expressed in terms of ±1 or i itself.
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答案1
您收到的错误消息是：
! Undefined control sequence. l.35 \chapter
您收到此错误消息，因为您不能chapter与 documentclass 结合使用article。
您有以下两种可能性：
- 请使用
reportdocumentclass 来代替。 - 保留 documentclass
article并替换\chapter为\section。