Answer:
If you have a quantity X of a substance, with a decay constant r, then the equation that tells you the amount of substance that you have, at a time t, is:
C(t) = X*e^(-r*t)
Now, we know that:
We have 2000g of substance A, and it has a decay constant of 0.03 (i assume that is in 1/year because the question asks in years)
And we have 3000 grams of substance B, with a decay constant of 0.05.
Then the equations for both of them will be:
Ca = 2000g*e^(-0.03*t)
Cb = 3000g*e^(-0.05*t)
Where t is in years.
We want to find the value of t such that Ca = Cb.
So we need to solve:
2000g*e^(-0.03*t) = 3000g*e^(-0.05*t)
e^(-0.03*t) = (3/2)e^(-0.05*t)
e^(-0.03*t)/e^(-0.05*t) = 3/2
e^(t*(0.05 - 0.03)) = 3/2
e^(t*0.02) = 3/2
Now we can apply Ln(x) to both sides, and get:
Ln(e^(t*0.02)) = Ln(3/2)
t*0.02 = Ln(3/2)
t = Ln(3/2)/0.02 = 20.3
Then after 20.3 years, both substances will have the same mass.
First, find the measure of an interior angle:
the sum of the interior angles of a polygon is (n-2)*180, n is the number of sides
for a 15-sided polygon, the sum is 13*180
each interior angle is then 13*180/15=156
the measure of each exterior angle=180-156=24
Answer:
9, 10
Step-by-step explanation:
square root of √93 is 9.64.
Thus, we see that the number 9.64 is greater than but less than 10.
On number line it can be represented as
-∞ _____________7___8___9__9.64___10___11_______+∞
Thus, we see that the two whole numbers between which √93 lies is 9, 10
Answer:
C) 8
Step-by-step explanation:
-5(a+3)=-55
a+3=-55/-5
a+3=11
a=11-3
a=8
Answer:
5x² - 10x - 15 = 0
Step-by-step explanation:
Given that the roots are x = 3 and x = - 1, then the factors are
(x - 3) and (x + 1) and the quadratic is the product of the factors, that is
f(x) = a(x - 3)(x + 1) ← a is a multiplier
Here a = 5, thus
f(x) = 5(x - 3)(x + 1) ← expand factors using FOIL
= 5(x² - 2x - 3) ← distribute parenthesis by 5
= 5x² - 10x - 15
Thus equation is
5x² - 10x - 15 = 0
