28. (a) |w + z| = sqrt(62 + (-2)2) = sqrt(40)
(b) |w - z| = sqrt((-2)2 + (-4)2) = sqrt(20)
(c) |w*z| = sqrt((11)2 + (-10)2) = sqrt(221)
(d) |w/z| = sqrt((5)2 + (-14)2)/sqrt(17) = sqrt(221)/sqrt(17) = sqrt(221/17)
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