Answer:
- (x-4.5)^2 +(y +5)^2 = 30.25
- x = (1/8)y^2 +(1/2)y +(1/2)
- y^2/36 -x^2/64 = 1
- x^2/16 +y^2/25 = 1
Step-by-step explanation:
1. Complete the square for both x and y by adding a constant equal to the square of half the linear term coefficient. Subtract 15, and rearrange to standard form.
(x^2 -9x +4.5^2) +(y^2 +10y +5^2) = 4.5^2 +5^2 -15
(x -4.5)^2 +(y +5)^2 = 30.25 . . . . . write in standard form
Important features: center = (4.5, -5); radius = 5.5.
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2. To put this in the form x=f(y), we need to add 8x, then divide by 8.
x = (1/8)y^2 +(1/2)y +(1/2)
Important features: vertex = (0, -2); focus = (2, -2); horizontal compression factor = 1/8.
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3. We want y^2/a^2 -x^2/b^2 = 1 with a=36 and b=(36/(3/4)^2) = 64:
y^2/36 -x^2/64 = 1
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4. In the form below, "a" is the semi-axis in the x-direction. Here, that is 8/2 = 4. "b" is the semi-axis in the y-direction, which is 5 in this case. We want x^2/a^2 +y^2/b^2 = 1 with a=4 and b=5.
x^2/16 +b^2/25 = 1
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The first attachment shows the circle and parabola; the second shows the hyperbola and ellipse.
Have a cat: 17
Don't have a cat: 15
Have a dog: 21
Don't have a dog: 11
For the "have a..." you include the center, but for the "don't have a..." you only count the other side without the center.
We'll use variables to represent the speeds of the eastbound and westbound trains.
x will represent the speed of the eastbound train.
y will represent the speed of the westbound train.
The eastbound train is 16 mph faster than the westbound train. An equation can be made from this:
Subtraction is used, because it represents the difference in distances between the two trains if they travel the same direction.
After 4 hours, the trains are 800 miles apart. An equation can be made from this:
Addition is used, because the trains are heading in opposite directions, which means their distances from the starting point are added together.
Set the two equations up vertically:
We will use elimination to solve for x.
Multiply the entire first equation by 4 so that the coefficients for y will be opposite numbers:
Combine the two equations together to cancel out y:
Divide both sides by 8 to get x by itself:
The speed of the eastbound train is
108 mph.
Answer:
C =(43/55)R; C - R = 8t; 48 mi
Step-by-step explanation:
Let C = the distance a coyote can run in t hours.
Let R = the distance a rabbit can run in t hours.
(1) C = 43t
(2) R = 35t
A. <em>Two equivalent expressions
</em>
(a) C/R = 43/35
C = (43/55)R
(b) C – R = 43t – 35t
C – R = 8t
B. <em>Distance advantage of coyote
</em>
Let the difference D = C - R
D = 8t
D = 8 × 6
D = 48 mi
In 6 h, the coyote can run 48 mi further than the rabbit.
