Let z is equal to 9 minus 2 i and z w is equal to 25 plus 70 i What is w ?

Since zw = 25 + 70i and z = 9 − 2i, divide to find w: w = (25 + 70i)/(9 − 2i). Multiply the numerator and denominator by the conjugate, 9 + 2i, to get (85 + 680i)/85 = 1 + 8i. Therefore, w is 1 plus 8i, choice A.

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