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Question -

Evaluate the following:

(i) i 457

(ii) i 528

(iii) 1/ i58

(iv) i 37 + 1/i 67

(v) [i 41 + 1/i 257]

(vi) (i 77 + i 70 + i 87 +i 414)3

(vii) i 30 + i 40 + i 60

(viii) i 49 + i 68 + i 89 +i 110



Answer -

(i) i 457

Let us simplify weget,

i457 =i (456 + 1)

= i 4(114) ×i

= (1)114 ×i

= i [since i4 =1]

(ii) i 528

Let us simplify weget,

528 =i 4(132)

= (1)132

= 1 [since i4 =1]

(iii) 1/ i58

Let us simplify weget,

1/ i58 =1/ i 56+2

= 1/ i 56 ×i2

= 1/ (i4)14 ×i2

= 1/ i2 [since,i4 = 1]

= 1/-1 [since, i2 =-1]

= -1

(iv) 37 +1/i 67

Let us simplify weget,

37 +1/i 67 = i36+1 + 1/ i64+3

= i + 1/i3 [since,i4 = 1]

= i + i/i4

= i + i

= 2i

(v) [i 41 +1/i 257]

Let us simplify weget,

[i 41 +1/i 257] = [i40+1 + 1/ i256+1]

= [i + 1/i]9 [since,1/i = -1]

= [i – i]

= 0

(vi) (i 77 +i 70 + i 87 + i 414)3

Let us simplify weget,

(i 77 +i 70 + i 87 + i 414)=(i(76 + 1) + i(68 + 2) + i(84 + 3) +i(412 + 2) ) 3

= (i + i2 +i3 + i2)3 [since i3 =– i, i2 = – 1]

= (i + (– 1) + (– i) +(– 1)) 3

= (– 2)3

= – 8

(vii) 30 +i 40 + i 60

Let us simplify weget,

30 +i 40 + i 60 = i(28 + 2) + i40 +i60

= (i4)7 i2 +(i4)10 + (i4)15

= i2 +110 + 115

= – 1 + 1 + 1

= 1

(viii) 49 +i 68 + i 89 + i 110

Let us simplify weget,

49 +i 68 + i 89 + i 110 =i(48 + 1) + i68 + i(88 + 1) + i(116+ 2)

= (i4)12×i+ (i4)17 + (i4)22×i + (i4)29×i2

= i + 1 + i – 1

= 2i

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