Problem PageQuestion The mass of a radioactive substance follows a continuous exponential decay model, with a decay rate parameter of per day. Find the half-life of this substance (that is, the time it takes for one-half the original amount in a given sample of this substance to decay).

8.55 days for a decay rate parameter of 8.1% per day

Step-by-step explanation:

Assuming a decay rate parameter of  8.1% per day

the general equation for radioactive decay is;

N = N₀e^(-λt)

x - decay constant (λ) - rate of decay 

t-  time 

N - amount remaining after t days , since we are calculating the half life, amount of time it takes for the substance to to be half its original value, its N₀/2

N₀ - amount initially present 

substituting the values 

N₀/2 = N₀e^(-0.081t)

0.5 = e^(-0.081t)

ln (0.5) = -0.081t

-0.693 = -0.081t

t = 0.693 / 0.081  = 8.55

half life of substance is 8.55 days 

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step-by-step explanation:

answer: (-8,4) are the coordinates of a

step-by-step explanation:

let the side of square abcd is x .

thus the area of square abcd is .

now, by the diagram area of triangle ead= 1/2 × ea × ad = 1/2 × ea × x

( because ad is the side of square)

and, according to the question,

the areas of square abcd and right ead are equal.

⇒

⇒ea=2x

thus, ea: ab=2: 1

therefore, point a divides line segment eb into the ratio 2: 1.

⇒ by sectional formula coordinates of a are,

=

=

=(-8, 4)

thus the coordinates of a are (-8,4)