Sharee and her two sisters ate 3 5 of a pizza. How much of the pizza did each girl have? A) 1 3 B) 1 5 C) 2 15 D) 3 10
1 answer:
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Let's call L the width of the rectangle and W its width. The area of the rectangle is the product between the length and the width, and we are also told that the area is 300 square meters, so we can write
Moreover, we know that the length is 5 meters longer than the width:
We have a system of 2 equations in 2 unknown variables, L and W. If we substitute the second equation into the first one, we get
which has two solutions: W=-20 and W=15. We can discard the negative solution since it does not have physical meaning, and now we can substitute the value of W into the second equation to find L:
<span>Therefore, the rectangle has width 15 meters and length 20 meters.</span>
Moreover, we know that the length is 5 meters longer than the width:
We have a system of 2 equations in 2 unknown variables, L and W. If we substitute the second equation into the first one, we get
which has two solutions: W=-20 and W=15. We can discard the negative solution since it does not have physical meaning, and now we can substitute the value of W into the second equation to find L:
<span>Therefore, the rectangle has width 15 meters and length 20 meters.</span>
Answer:
The value of x that gives the maximum transmission is 1/√e ≅0.607
Step-by-step explanation:
Lets call f the rate function f. Note that f(x) = k * x^2ln(1/x), where k is a positive constant (this is because f is proportional to the other expression). In order to compute the maximum of f in (0,1), we derivate f, using the product rule.
We need to equalize f' to 0
- k*(2x ln(1/x) - x) = 0 -------- We send k dividing to the other side
- 2x ln(1/x) - x = 0 -------- Now we take the x and move it to the other side
- 2x ln(1/x) = x -- Now, we send 2x dividing (note that x>0, so we can divide)
- ln(1/x) = x/2x = 1/2 ------- we send the natural logarithm as exp
- 1/x = e^(1/2)
- x = 1/e^(1/2) = 1/√e ≅ 0.607
Thus, the value of x that gives the maximum transmission is 1/√e.
