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3 years ago

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If x+yi/i = 8+ 10i, where x and y are real, what is the value of (x + yi)(x - yi)?

2 answers:

Shalnov [3]3 years ago

5 0

Answer:

164

Step-by-step explanation:

(x + iy)/i = 8 + 10i

(x + iy) = (8 + 10i)(i) = 8i + 10i²

= -10 + 8i

(-10 + 8i)(-10 - 8i) = (-10)² + 8² = 164

Nutka1998 [239]3 years ago

3 0

Answer:

A.164

Step-by-step explanation:

(x+yi)(x-yi) -> (8+10i)(8-10i)

<em>rule: *(a-b)(a+b)=a^2+b^2</em>

(8+10i)(8-10i) = 64-100i^2

<em>rule: i^2=(-1)</em>

64-100i^2 = 64-100(-1)

=64+100

=164

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