Simplify each of the following and express it in the form (a + ib) :

(5 – 2i)2


Given: (5 – 2i)2

We know that,


(a – b)2 = a2 + b2 – 2ab …(i)


So, on replacing a by 5 and b by 2i in eq. (i), we get


(5)2 + (2i)2 – 2(5)(2i)


= 25 + 4i2 – 20i


= 25 – 4 – 20i [∵ i2 = -1]


= 21 – 20i



1