Y=4x-2y and y=x+3 estimate the solutions to the systems of equations
1 answer:
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Answer:
- B. 191.4 m²
Step-by-step explanation:
Split the trapezoid as pictured below
Find its height and the upper base, then find the area of the trapezoid.
There are 3 pieces, two of them are 45°×45° and 30°×60°×90° triangles
- The ratio of sides of a 30°×60°×90° triangle is 1 : √3 : 2
- The legs of a 45x45 triangle are equal
<u>The above mentioned properties give us:</u>
- h = 16/2 = 8 m
- b = 8√3 ≈ 13.85 m
- a = h = 8 m
<u>Now find the area:</u>
- A = 1/2( 13 + 8 + 13.85 + 13)*8 = 191.4 m²
Correct choice is B
Answer:
a. A(x) = (1/2)x(9 -x^2)
b. x > 0 . . . or . . . 0 < x < 3 (see below)
c. A(2) = 5
d. x = √3; A(√3) = 3√3
Step-by-step explanation:
a. The area is computed in the usual way, as half the product of the base and height of the triangle. Here, the base is x, and the height is y, so the area is ...
A(x) = (1/2)(x)(y)
A(x) = (1/2)(x)(9-x^2)
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b. The problem statement defines two of the triangle vertices only for x > 0. However, we note that for x > 3, the y-coordinate of one of the vertices is negative. Straightforward application of the area formula in Part A will result in negative areas for x > 3, so a reasonable domain might be (0, 3).
On the other hand, the geometrical concept of a line segment and of a triangle does not admit negative line lengths. Hence the area for a triangle with its vertex below the x-axis (green in the figure) will also be considered to be positive. In that event, the domain of A(x) = (1/2)(x)|9 -x^2| will be (0, ∞).
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c. A(2) = (1/2)(2)(9 -2^2) = 5
The area is 5 when x=2.
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d. On the interval (0, 3), the value of x that maximizes area is x=√3. If we consider the domain to be all positive real numbers, then there is no maximum area (blue dashed curve on the graph).
