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1. COMPLEX NUMBERS, , e Introduction:, _e We introduce a symbol i (Greek letter iota) such, thati = V—landi? = —1., e tis called as an imaginary unit or an imaginary, number., , e Swiss mathematician Leonard Euler (17071783) was the first mathematician to introduce, , the symbol i withi = V—1 andi? = —1.

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1.1 (b) Complex Number :, , Definition: A number of the form a+ib,where a,b €R and, i =V—1 withi? = —1 iscalleda complex number, and itis usually denoted by z., Thatisz = a+ib, a,b€R andi =vV—-1, Where 1) ais called the real part of z and, itis denoted by Re(z) or R(z)., 2) bis called imaginary part of z and, is denoted by Im(z) or I(z), The set of complex numbers is denoted by C, » C = {atib/abe R,and i= -v-1}