Answer:
x > 9.
Step-by-step explanation:
Here it is just simplifying the inequality.
6 - 2/3x < x - 9
Add 2/3x to both sides.
6 < 5/3x - 9
Add 9 to both sides.
15 < 5/3x
Multiply by 3/5.
9 < x
Flip it.
x > 9.
This just wants the derivative which you can solve for.
You can do this using a negative expononet or using ...the rational rule forget its name*.... you shoudl get 9000/(t+12)^2
*Quotient rule
Answer:

Step-by-step explanation:
to find the surface area we need to find the followng areas:
- area of a triangle and multiply it by 4 (because there are 4 triangles)
And once we have those areas, we add them to find the surface area.
Area of the square:
the formula to find the area of a square is:

where
is the length of the side: 
thus the area of the square is:


Area of the triangles:
the are of 1 triangle is given by

where
is the base of the triangle:
(the base of the triangle is the side of the square)
and
is the height of the triangle: 
thus, the area of 1 triangle is:



the area of the 4 triangles is (we multiply by 4):


finally we add the area of the square and the area of the 4 triangles to find the total surface area:

