Answers:
Part A: 12y² + 10y – 21
Part B: 4y³ + 6y² + 6y – 5
Part C: See below.
Explanations:
Part A:
For this part, you add Sides 1, 2 and 3 together by combining like terms:
Side 1 = 3y² + 2y – 6
Side 2 = 4y² + 3y – 7
Side 3 = 5y² + 5y – 8
3y² + 2y – 6 + 4y² + 3y – 7 + 5y² + 5y – 8
Combine like terms:
3y² + 4y² + 5y² + 2y + 3y + 5y – 6 – 7 – 8
12y² + 10y – 21
Part B:
You have the total perimeter and the sum of three of the sides, so you just need that fourth side value, which we can call d.
P = 4y³ + 18y² + 16y – 26
Sides 1, 2 & 3 = 12y² + 10y – 21
Create an algebraic expression:
12y² + 10y – 21 + d = 4y³ + 18y² + 16y – 26
Solve for d:
12y² + 10y – 21 + d = 4y³ + 18y² + 16y – 26
– 12y² – 12y²
10y – 21 + d = 4y³ + 6y² + 16y – 26
– 10y – 10y
– 21 + d = 4y³ + 6y² + 6y – 26
+ 21 + 21
d = 4y³ + 6y² + 6y – 5
Part C:
If closed means that the degree that these polynomials are at stay that way, then yes, this is true in these cases because you will notice that each side had a y², y and no coefficient value except for the fourth one. This didn't change, because you only add and subtract like terms.
Answer:
D
Step-by-step explanation:

Answer:
1.3 pounds
Step-by-step explanation:
-4x + 7y = -8 . . . (1)
-5x + 6y = 1 . . . .(2)
(1) x 5 => -20x + 35y = -40 . . . (3)
(2) x 4 => -20x + 24y = 4 . . . . .(4)
(3) - (4) => 11y = -44 => y = -44/11 = -4
From (2), -5x + 6(-4) = 1 => -5x - 24 = 1 => -5x = 1 + 24 = 25 => x = 25/-5 = -5
Therefore, x = -5, y = -4
Your answer is the second option: The surface area of B is greater than the surface area of A.
To find the surface area, I found the area of the three sides shown and added them together, and then multiplied the answer by 2, so:
B:
8 × 2 = 16
8 × 10 = 80
10 × 2 = 20
+
= 116
116 × 2 = 232 cm²
A:
5 × 8 = 40
5 × 4 = 20
8 × 4 = 32
+
= 92
92 × 2 = 184 cm²
So therefore B > A because 232 > 184
I hope this helps!