Which pair of complex factors results in a real number product? 15(–15i) 3i(1 – 3i) (8 + 20i)(–8 – 20i) (4 + 7i)(4 – 7i)

(4 + 7i)(4 – 7i)

Step-by-step explanation:

This pair will produce a real answer because they are complex conjugates.

Complex conjugates ( a+bi) (a-bi)  when multiplied together form a real number ( a^2 + b^2)

(n^3 - n)

= n(n-1)(n+1)

since it is divisible by 3 and 2 ,because it is a multiple 3 consecutive number

if, n-1 is odd then n+1 is also odd, then it is a multiple of 9

but if, n-1 is even then n+1 is also even, then it is a multiple of 4

so, largest multiple = max(9*2, 4*3) = max(18, 12) = 18

step-by-step explanation:

in which figure is point g a centroid