It -2 because a negative times a positive is a negative
Answer:
see below
Step-by-step explanation:
The equation for half life is
n = no e ^ (-kt)
Where no is the initial amount of a substance , k is the constant of decay and t is the time
no = 9.8
1/2 of that amount is 4.9 so n = 4.9 and t = 100 years
4.9 = 9.8 e^ (-k 100)
Divide each side by 9.8
1/2 = e ^ -100k
Take the natural log of each side
ln(1/2) = ln(e^(-100k))
ln(1/2) = -100k
Divide each side by -100
-ln(.5)/100 = k
Our equation in years is
n = 9.8 e ^ (ln.5)/100 t)
Approximating ln(.5)/100 =-.006931472
n = 9.8 e^(-.006931472 t) when t is in years
Now changing to days
100 years = 100*365 days/year
36500 days
Substituting this in for t
4.9 = 9.8 e^ (-k 36500)
Take the natural log of each side
ln(1/2) = ln(e^(-36500k))
ln(1/2) = -36500k
Divide each side by -100
-ln(.5)/36500 = k
Our equation in years is
n = 9.8 e ^ (ln.5)/36500 d)
Approximating ln(.5)/365=-.00001899
n = 9.8 e^(-.00001899 d) when d is in days
Answer:too hard (ywan emoji)
Step-by-step explanation:
Answer:
88 cm²
Step-by-step explanation:
w = x
l = x + 3
P = 38
We know that 
, so we substitute known values:
Therefore, we know that the width (x) is 8 cm and the length (x + 3) is 8 + 3 = 11 cm. To verify, we can check that the perimeter equals 38:
8 + 11 + 8 + 11 = 38. <em>Check.</em>
Thus, the area of the rectangle is:
Therefore, the area is 88 cm².
