Question

For what real number k does the product (25 + ki)(3+2i) equal a real number?

Answer 1

Hello : 
(25 + ki)(3+2i) = 75+50i +3ki -2k = (75-2k) +i (3k+50)
the product (25 + ki)(3+2i) equal a real number: 3k +50 = 0
k = -50/3