Any product of any list of factors is zero, if one of the factors is zero.
8 and 5 are factors of 40.
8, 40 and 200
74 and 40
You didn't bother to list the binomials to choose from, but the two binomial factors of x2 + 6x - 40 are (x + 10) and (x - 4)
40 and 21 have no common prime factors
45 and 40
16/40 + 15/40 = 31/40
this equals 818
The two prime factors of 40 are: 2 and 5
40
7 40 plus 2 as the sum of two products can be expressed as 1.47 x 1.47.