C = 2πR ⇒ R = C/2π = 12/2π = 6/π ≈ 6/3,14 = 600/314 ≈ 1.91
Answer:
Option A is correct, i.e. 3 mph.
Step-by-step explanation:
Tinh can row at a rate of 6 mph in still water.
Suppose the speed of the river current is X mph.
Then Upstream speed = (6-X) mph.
And Downstream speed = (6+X) mph.
It takes her 2 hours to row upstream from a dock to a park. She then rows back to the dock, and it only takes 40 minutes.
It means Distance upstream = Distance downstream.
Speed upstream x Time upstream = Speed downstream x Time downstream.
(6-x) * 2 = (6+x) * 40/60
12 - 2x = 4 + 2x/3
12 - 4 = 2x/3 + 2x
8 = 2x/3 + 6x/3 = 8x/3
x = 3 mph.
Hence, option A is correct, i.e. 3 mph.
Answer:
Step-by-step explanation:
Let's call hens h and ducks d. The first algebraic equation says that 6 hens (6h) plus (+) 1 duck (1d) cost (=) 40.
The second algebraic equations says that 4 hens (4h) plus (+) 3 ducks (3d) cost (=) 36.
The system is
6h + 1d = 40
4h + 3d = 36
The best way to go about this is to solve it by substitution since we have a 1d in the first equation. We will solve that equation for d since that makes the most sense algebraically. Doing that,
1d = 40 - 6h.
Now that we know what d equals, we can sub it into the second equation where we see a d. In order,
4h + 3d = 36 becomes
4h + 3(40 - 6h) = 36 and then simplify. By substituting into the second equation we eliminated one of the variables. You can only have 1 unknown in a single equation, and now we do!
4h + 120 - 18h = 36 and
-14h = -84 so
h = 6.
That means that each hen costs $6. Since the cost of a duck is found in the bold print equation above, we will sub in a 6 for h to solve for d:
1d = 40 - 6(6) and
d = 40 - 36 so
d = 4.
That means that each duck costs $4.
It is 3i.
The square root of -9 is the square root of -1 times the square root of 9.
So: the square root of 9 is 3, and the square root of -1 is called i (this doesn't actually exist, it's just imaginary).
Then, the square root of -9 is 3i.
Answer:
The opposite or absolute value is 5.2
