Answer:
C
Step-by-step explanation:
The area (A) of a regular decagon is
A = perimeter × apothem
perimeter = 10 × 8 = 80 in, thus
A = 0.5 × 80 × 12.3 = 492 in² → D
Answer:
4x^2+36x+81
Step-by-step explanation:
FOIL
First terms
Outside terms
inside terms
last terms
5y-4=9y+8
Subtract 5y from both sides
-4=4y+8
Subtract 8 from both sides
-12=4y
Divide both sides by 4
-3=y
Check by plugging it in:
5(-3)-4=9(-3)+8
-15-4=-27+8
-19=-19
True
Final answer: y=-3