Answer:
D. About 800 years
Step-by-step explanation:
Use the half-life equation:
A = A₀ (½)ⁿ
where A is the final amount,
A₀ is the initial amount,
and n is the number of half-lives.
0.90A₀ = A₀ (½)ⁿ
0.90 = (½)ⁿ
To solve for n, take log of both sides:
log 0.9 = n log 0.5
n = (log 0.9) / (log 0.5)
n = 0.152
It takes 0.152 half-lives. The half-life of carbon-14 is 5730 years.
0.152 × 5730 years = 871 years
The closest answer is D.
Let the side of the garden alone (without walkway) be x.
Then the area of the garden alone is x^2.
The walkway is made up as follows:
1) four rectangles of width 2 feet and length x, and
2) four squares, each of area 2^2 square feet.
The total walkway area is thus x^2 + 4(2^2) + 4(x*2).
We want to find the dimensions of the garden. To do this, we need to find the value of x.
Let's sum up the garden dimensions and the walkway dimensions:
x^2 + 4(2^2) + 4(x*2) = 196 sq ft
x^2 + 16 + 8x = 196 sq ft
x^2 + 8x - 180 = 0
(x-10(x+18) = 0
x=10 or x=-18. We must discard x=-18, since the side length can't be negative. We are left with x = 10 feet.
The garden dimensions are (10 feet)^2, or 100 square feet.
Answer:
Step-by-step explanation:
The missing details in the question are:
Required
The perimeter
This is calculated as:
So, we have:
Open bracket
Rewrite as:
Answer: (n+5)x(n+1)
Step-by-step explanation:
1. Write 6n as a sum
2. Factor out n form the expression
3. Factor out n+5 from the expression
(n+5)x(n+1)
Answer:
On this case n =6 and x =6 we got:
Step-by-step explanation:
The utility for the combination formula is in order to find the number of ways to order a set of elements
For this case we want to find the following expression:
And the general formula for combination is given by:
On this case n =6 and x =6 we got:
