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nlexa [21]
3 years ago
15

Radioactive material disintegrates at a rate proportional to the amount currently present. If Q(t) is the amount present at time

t (in weeks), then dQ dt = −rQ, where r > 0 is the decay rate.
A) If 500 mg of a mystery substance decays to 83.01 mg in 5 weeks, determine the decay rate r.
B) Find an expression for the amount of this substance present at any time t.
C) Find the time required for the substance to decay to one-half its original amount.

Mathematics
1 answer:
stepladder [879]3 years ago
3 0

Answer:

Step-by-step explanation:

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Please help........................
ivanzaharov [21]

The volume of a sphere is 4/3 * pi * r³ so substitute the values in

4/3 * pi * 2³

4/3 * pi * 8

32/3 * pi

The volume is either 32/3pi units³ or 33.49 units³ (they're the same value)

I hope this helps!

6 0
2 years ago
Which function represents exponential decay
mamaluj [8]

 The formula for exponential growth and decay is: In this function, a symbolizes the origin value, such as the starting population or the beginning dosage level. The variable b represents the growth or decay factor. If b > 1, the function signifies exponential growth.

4 0
3 years ago
Evaluate the following integrals: 1. Z x 4 ln x dx 2. Z arcsin y dy 3. Z e −θ cos(3θ) dθ 4. Z 1 0 x 3 √ 4 + x 2 dx 5. Z π/8 0 co
Zigmanuir [339]

Answer:

The integrals was calculated.

Step-by-step explanation:

We calculate integrals, and we get:

1) ∫ x^4 ln(x) dx=\frac{x^5 · ln(x)}{5} - \frac{x^5}{25}

2) ∫ arcsin(y) dy= y arcsin(y)+\sqrt{1-y²}

3) ∫ e^{-θ} cos(3θ) dθ = \frac{e^{-θ} ( 3sin(3θ)-cos(3θ) )}{10}

4) \int\limits^1_0 {x^3 · \sqrt{4+x^2} } \, dx = \frac{x²(x²+4)^{3/2}}{5} - \frac{8(x²+4)^{3/2}}{15} = \frac{64}{15} - \frac{5^{3/2}}{3}

5)  \int\limits^{π/8}_0 {cos^4 (2x) } \, dx =\frac{sin(8x} + 8sin(4x)+24x}{6}=

=\frac{3π+8}{64}

6)  ∫ sin^3 (x) dx = \frac{cos^3 (x)}{3} - cos x

7) ∫ sec^4 (x) tan^3 (x) dx = \frac{tan^6(x)}{6} + \frac{tan^4(x)}{4}

8)  ∫ tan^5 (x) sec(x)  dx = \frac{sec^5 (x)}{5} -\frac{2sec^3 (x)}{3}+ sec x

6 0
3 years ago
I am an odd number. Take away one letter and I become even. What number am I?
Lady bird [3.3K]

Answer:

seven

Step-by-step explanation:

Lol thxx for the points

Pls give brainliest! Also, plz sub to kgirl633 on yt.

5 0
2 years ago
There are 16 entrees available at a restaurant. From these, Archie is to choose 6 for his party. How many groups of 6 entrees ca
Vikki [24]

Answer:

8008

Step-by-step explanation:

This is the selection of 6 elements out of 16 elements. Applying the combination formula, the total number of selections is nCr with n =16 and r =6.

16C6 = 8008

3 0
3 years ago
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