(x - 8)(x - 5)
Any product of any list of factors is zero, if one of the factors is zero.
Well, honey, in the equation 8x5=40, the two factors are 8 and 5. 8 times 5 equals 40. It's as simple as that, darling.
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)
8, 40 and 200
74 and 40
16/40 + 15/40 = 31/40
this equals 818
40
7 40 plus 2 as the sum of two products can be expressed as 1.47 x 1.47.
25/40 + 16/40 = 41/40 = 1 and 1/40
40 and 21 have no common prime factors
You should look for two numbers whose product is 40, and whose sum is 13. Experimenting a little (trying different pairs of factors for 40), you can quickly realize that this works for 8 and 5. Therefore, x2 + 13x + 40 = (x + 8) (x + 5)