None of these couples are solutions, (11, 3)(11, 3); (−1, −6)(−1, −6); (−3, 3)(−3, 3); <span>(7, 0). Perhaps the choice of answer are insufficient. we can add (1, 48) the couple (7, 0) and (7, 0)(1, 48) is a true answer, why? because it verifies the equation.</span>
The answer is the first one because you have to multiply the outsider five to the other numbers inside the parenthesis. You don't add them or subtract them because they don't have the same variable
Y is going to be the number 40
x will equal 90
This is a simple problem based on combinatorics which can be easily tackled by using inclusion-exclusion principle.
We are asked to find number of positive integers less than 1,000,000 that are not divisible by 6 or 4.
let n be the number of positive integers.
∴ 1≤n≤999,999
Let c₁ be the set of numbers divisible by 6 and c₂ be the set of numbers divisible by 4.
Let N(c₁) be the number of elements in set c₁ and N(c₂) be the number of elements in set c₂.
∴N(c₁) =

N(c₂) =

∴N(c₁c₂) =

∴ Number of positive integers that are not divisible by 4 or 6,
N(c₁`c₂`) = 999,999 - (166666+250000) + 41667 = 625000
Therefore, 625000 integers are not divisible by 6 or 4