How do you simplify (−3+i)(2+7i)?

1 Answer
Lucio Falabella
Jan 22, 2016

(−3+i)(2+7i)=−13−19i=−(13+19i)

Explanation:

Remembering that i2=−1

You can think that (a+ib) is like a binomial, thus:

(−3+i)(2+7i)=(−3×2−3×7i+2×i+7i2)=

=−6−21i+2i+7×(−1)=(−6−7)+(−21+2)i=−13−19i=−(13+19i)

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