The area of a circle is A = πr^2. We let A1 And A2 the areas of the circles and r1 and r2 the radius of each, respectivley.
A1 + A2 = 80π
Substitute the formula for the area,
π(r1)^2 + π (r2)^2 = 80π
From the statement, we know that r2=2(r1).
<span>π(r1)^2 + π (2 x r1)^2 = 80π
</span>We can cancel π, we will have
5 x (r1)^2 = 80
Thus,
r1 = 4 and r2 = 8
Surface area of a cube = 486 square inches
Solution:
Given each side of a cube = 9 inches
Net of a cube has 6 squares.
Area of square = side × side
Area of 1 square = 9 × 9 = 81 square inches
Surface area of a cube = Area of 6 squares
= 6 × (side × side)
= 6 × 81
= 486 square inches
Hence, surface area of a cube is 486 square inches.
Answer: t-half = ln(2) / λ ≈ 0.693 / λExplanation:The question is incomplete, so I did some research and found the complete question in internet.
The complete question is:
Suppose a radioactive sample initially contains
N0unstable nuclei. These nuclei will decay into stable
nuclei, and as they do, the number of unstable nuclei that remain,
N(t), will decrease with time. Although there is
no way for us to predict exactly when any one nucleus will decay,
we can write down an expression for the total number of unstable
nuclei that remain after a time t:
N(t)=No e−λt,
where λ is known as the decay constant. Note
that at t=0, N(t)=No, the
original number of unstable nuclei. N(t)
decreases exponentially with time, and as t approaches
infinity, the number of unstable nuclei that remain approaches
zero.
Part (A) Since at t=0,
N(t)=No, and at t=∞,
N(t)=0, there must be some time between zero and
infinity at which exactly half of the original number of nuclei
remain. Find an expression for this time, t half.
Express your answer in terms of N0 and/or
λ.
Answer:
1) Equation given:
← I used α instead of λ just for editing facility..
Where No is the initial number of nuclei.
2) Half of the initial number of nuclei:
N (t-half) = No / 2So, replace in the given equation:
3) Solving for α (remember α is λ)
αt ≈ 0.693
⇒ t = ln (2) / α ≈ 0.693 / α ← final answer when you change α for λ
Answer:
x ≥ 9 and x < 5
Step-by-step explanation:
See the line graph of a compound inequality shown in the attached photo.
Inequality has two parts. The right-hand part is shown by an arrow that is more than 9 and including 9.
So, the equation of inequality for this part is x ≥ 9.
Again, the left-hand part of the inequality graph shows another arrow which is less than 5 but not including 5.
So, the equation of inequality for this part is x < 5
Therefore, compound inequality is x ≥ 9 and x < 5 (Answer)