-5/-7 = 5/7 = 0.71428577142857... The decimal form of the fraction never ends, so 5/7 is not a rational number
solution is (x, y ) → (- 1, 4 )
y + 2x = 2 → (1)
y + 4x = 0 → (2)
subtract equation (1) from (2) to eliminate term in y
(y - y ) + (4x - 2x ) = (0 - 2 )
2x = - 2 ( divide both sides by 2 )
x = - 1
substitute x = - 1 in either (1) or (2) and solve for y
(1) → y - 2 = 2 ( add 2 to both sides )
y = 4
solution is (x, y ) → (- 1, 4 )
Answer: The correct answer is the second choice: "When any two polynomials are added, the result is always a polynomial."
When a set of numbers is "closed" under an operation, it means that the resulting output answer is the same type as the input.
For example, if you add 2x + 9 and 3x + 12, you get 5x + 21.
You started with 2 polynomials and you ended with a polynomial.
Volume of a cube with side lengths of 2, 2, and 2.
2³=8 m³
Volume of a cube with 4,4, and 4
4³=64 m³
Conclusion: The volume would be squared, or square rooted, depending on which way you are going.