Evaluate 6 + 4/a + b/3 when a = 4 and b = 3.
1 answer:
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Answer:
- (a) see attached
- (b) width: 2x; height: y = 9-x²
- (c) A=2x(9-x²) . . . 0 ≤ x ≤ 3
- (d) dA/dx = -6x² +18; x=±√3
- (e) 12√3 units²
Step-by-step explanation:
(a) The attachment shows the graph of the parabola in blue. It also shows an inscribed rectangle in black.
(b) The upper right point of the rectangle is shown in the attachment as (x, y). The dimension y is the height of the rectangle. The x-dimension is half the width of the rectangle, which is symmetrical about the y-axis. Hence the width is 2x.
(c) As with any rectangle, the area is the product of length and width:
... A = (2x)(9 -x²) . . . . . the attachment shows a graph of this
... A = -2x³ +18x . . . . . expanded form suitable for differentiation
A suitable domain for A is where both x and A are non-negative: 0 ≤ x ≤ 3.
(d) The derivative of A with respect to x is ...
... A' = -6x² +18
This is defined everywhere, so the critical values will be where A' = 0.
... 0 = -6x² +18
... 3 = x² . . . . . . . divide by -6, add 3
... √3 = x . . . . . . . -√3 is also a solution, but is not in the domain of A
(e) The rectangle will have its largest area where x=√3. That area is ...
... A = 2x(9 -x²) = 2√3(9 -(√3)²) = 2√3(6)
... A = 12√3 . . . . square units . . . . ≈ 20.785 units²
Answer:
1.4% is the maximum acceptable annual rate of growth such that the population must stay below 24 billion during the next 100 years.
Step-by-step explanation:
We are given the following in the question:
The exponential growth model is given by:
where k is the growth rate, t is time in years and is constant.
The world population is 5.9 billion in 2006.
Thus, t = 0 for 2006
We have to find the maximum acceptable annual rate of growth such that the population must stay below 24 billion during the next 100 years.
Putting these values in the growth model, we have,
1.4% is the maximum acceptable annual rate of growth such that the population must stay below 24 billion during the next 100 years.