2 times what = -4?
-2 does
-2 x 2 = -4
-4 time what = 8?
Again, -2.
-2 x -4 = 8
You could do this over and over again or make a table, or you can make a function.
f(n) = f(1) • r

f(1) in this case is 2.
f(n) = 2 • r

r is rate of change, which is -2.
f(n) = 2 • -2

To find the 12th number in the sequence, just substitute n for 12.
f(12) = 2 • -2

f(12) = 2 • -2

-2^11 = -2048
2 x -2048 = -4096
So
the 12th number in the sequence will be -4096.
Given:
radius = 30 cm
π = 3.14
Find: Area of the top surface of a circular manhole cover.
Area of a circle = π r²
Area of a circle = 3.14 * (30cm)²
= 3.14 * 900 cm²
Area of a circle = 2,826 cm²
The area of the top surface of a circular manhole cover is 2,826 cm²