Find the center of the circle: x2 + 2x - 3 + y2 = 5.
1 answer:
Answer:
Step-by-step explanation:
x² + 2x - 3 + y² = 5
Strategy:
Convert the equation to the centre-radius form:
(x - h)² + (y - k)² = r²
The centre of the circle is at (h, k) and the radius is r .
Solution:
Move the number to the right-hand side.
x² + 2x + y² = 8
Complete the square for x
(Take half the coefficient of x, square it, and add to each side of the equation)
(x² + 2x + 1) + y² = 9
Complete the square for y
The coefficient of y is zero.
(x² + 2x + 1) + y² = 9
Express the result as the sum of squares
(x + 1)² + y² = 3²
h = -1; k = 0; r = 3
The centre of the circle is at
The graph of the circle below has its centre at (-1,0) and radius 3.
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Answer:
C and D
Step-by-step explanation:
Population density is the ratio of population to area. Its units are persons per square mile. Here, you're being asked to compare the population densities of several countries to the average population density in several US states.
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<h3>average</h3>The idea of "average population density of the 10 states listed" is somewhat ambiguous. It could mean either of (a) the ratio of the total of the states' population to the total of their land area, or (b) the average of the population densities of the states. (In the attached, we computed both, but the answer remains the same using either number.)
When there are numerous identical calculations to be performed, it is convenient to let a spreadsheet do them. The attached spreadsheet shows the population densities for the 10 states and 5 countries listed.
Depending on how you define it, the average population density of the 10 states is about 10.5 or about 15.7 people per square mile. (15.7 is the average of the density numbers, found using the spreadsheet AVERAGE function.)
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<h3>countries</h3>The 5 countries have population densities ranging from about 7.7 to 236 people per square mile. Two of the countries have density below 10.5, so are the answers to the question asked.
Canada (C) and Iceland (D) have population density below the US state average.
