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secondary 4 | E Maths
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Germaine
Germaine

secondary 4 chevron_right E Maths chevron_right Singapore

If z = 8 + 3i, then z^2 = ?

Date Posted: 3 years ago
Views: 592

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Rachel Tay
Rachel Tay's answer
4 answers (Tutor Details)
1st
hi! you can dm me @ssagajii on ig next time if you need help as i might not be so active here to check around! but anyways heres my ans to ur qn, hope it helps (and correct HAHHAA)
Eric Nicholas K
Eric Nicholas K
3 years ago
You missed that z = 8 + 3i is a complex number where i represents the imaginary number with a value equal to the square root of -1. The letter i here is not intended to be just another algebraic letter.

In other words, i² = -1, so your answer could be simplified further.

(This is covered either in the A Levels or some Poly courses)

So, z²
= (as you wrote)
= 9i² + 48i + 64
= 9 (-1) + 48i + 61
= -9 + 48i + 64
= 55 + 48i