Answer:
Perimeter 14x + 6 units
Area 12x^2 + 9x
At x = 8
Perimeter is 118 units
Area is 840 square units
Step-by-step explanation:
The perimeter of the rectangle is 2(l + b)
= 2(4x + 3 + 3x) = 2(7x + 3) = 14x + 6 units
The area of the rectangle is L * B = 3x(4x + 3)
opening the bracket, we have 12x^2 + 9x units
As x = 8
We substitute the value of x in each of the area and perimeter
for perimeter 14x + 6 = 14(8) + 6 = 112 + 6 = 118 units
For the area
12x^2 + 9x = 12(8)^2 + 9(8) = 768 + 72 = 840 square units
