Answer:
A.
C.
A.
Explanation:
Problem 1.
In a rectangle, opposite sides are congruent.
Two sides have length 4x^2 and two sides have length y^2.
perimeter = sum of the length of the sides
perimeter = 4x^2 + 4x^2 + y^2 + y^2
perimeter = 8x^2 + 2y^2
Choice A.
Problem 2.
(x^2 - 3x + 8) - (7x^2 - 2x - 1) =
Remove the first set of parentheses because they are not needed.
= x^2 - 3x + 8 - (7x^2 - 2x - 1) =
Think of the negative side tot eh left of the second set of parentheses as a -1 that needs to be distributed. Multiply each term inside the second set of parentheses by -1.
= x^2 - 3x + 8 -7x^2 + 2x + 1
Combine like terms.
= -6x^2 - x + 9
Choice C.
Problem 3.
You know the sum and one of the added terms. Subtract the known added term from the sum to find the other added term.
9x^2 - 4x - (3x^2 - 2x) =
As above, distribute teh negative sign by the second set of parentheses.
= 9x^2 - 4x - 3x^2 + 2x
= 6x^2 - 2x
Choice A.