The half life of the radioactive substance is 10.22 years.
<h3>What is Half Life ?</h3>
Half Life is the amount of time needed by the radioactive substance to reduce to its half concentration (as compared to the initial concentration).
It is given that
y = ae⁻ᵇˣ
here a is the initial amount , y is the amount remaining after x years
a = 90mg at x =0
Value of y = 12.6 mg at x = 29 years
On substitution of value
12.6 = 90 e⁻²⁹ᵇ
0.14 = e⁻²⁹ᵇ
b = 0.0678
The equation is
Half life is when the concentration is reduced to half
On 1st half life , the concentration = 90/2 = 45 mg
x = 10.22 years
Therefore the half life of the radioactive substance is 10.22 years.
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so the solution is 5 we'll start with that
x=5
to do reverse multiplcation, you must divide so
x=5
x/10=5/10
x/10=1/2
then the other problem
x=5
5x=25
to solvve
x/10=1/2
multiply by 10
x=5
then
5x=25
divide both sides by 5
x=5
Answer:
15.7 inches
Step-by-step explanation:
A clock is a circle . It tells us that the radius of the circle is 2.5 inches, and it is asking for the circumference. Therefore, we can use the equations for a circle to solve for the circumference.
Answer:
49°
Step-by-step explanation:
Given vectors:
a = [-8, 6]
B = [√7, 3]
θ = ?
To find the angle between the two vectors, we will be using the formula,
a.B = |a||B|cosθ
For simplicity, it is good to first calculate the dot product, and the magnitudes. Then we will substitute the values of the dot product, and the magnitudes of the vectors to solve for the angle.
Calculating the dot product
a.B = (-8, 6) . (√7, 3)
= (-8 × √7) + (6 × 3)
= -8√7 + 18
= 18 - 8√7
= 10√7
Calculating the magnitude the vectors
1. The magnitude of vector (-8, 6)
2. The magnitude of vector (√7, 3)
Calculating the angle between the vectors,
cosθ = 
cosθ = 
cosθ = 0.6614
θ = cos⁻¹0.6614
θ = 48.59°
θ = 49°
