Maddy took a test with 25 questions. She lost 3 points for each of the 3 questions she got wrong, but she got 2 extra credit que
1 answer:
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Answer:
Speed of boat in still water is 6km/h
Speed of current is 4km/h
Step-by-step explanation:
We know speed = distance / time
Let the speed of boat in still water be x
Let the speed of current be y
Hence the speed of boat, down stream =
Distance downstream = 20km
Time taken = 2 hours
We have
......(1)
Speed of boat upstream =
Distance upstream = 4
Time taken = 2
We have
...(2)
Adding (1) & (2)
Substituting in (1) we get
Refer to the figure shown below.
The point c, on line segment ab, is in a 3:1 ratio from a.
Therefore,
the x-coordinate of c is -1 +(3/4)*(3) = 5/4 = 1.25.
the y-coordinate of c is 1 - (3/4)*(2) = -1/2 = -0.5.
At point p(x,y), we want d1 = 3d₂, or d₁² = 9d₂².
Therefore
(x + 1)² + (y - 1)² = 9[(x - 2)² + (y + 1)²]
x² + 2x + 1 + y² - 2y + 1 = 9x² - 36x + 36 + 9y² + 18y + 9
8x² - 38x + 8y² + 20y + 43 = 0
x² - 4.75x + y² + 2.5y + 5.375 = 0
(x - 2.375)² - 5.6406 + (y + 1.25)² - 1.5625 + 5.375 = 0
(x - 2.375)² + (y + 1.25)² = 1.828
This is a circle with center at (2.375, -1.25) and radius 1.352.
Answer:
(x - 2.375)² + (y +1.25)² = 1.828
The point c, on line segment ab, is in a 3:1 ratio from a.
Therefore,
the x-coordinate of c is -1 +(3/4)*(3) = 5/4 = 1.25.
the y-coordinate of c is 1 - (3/4)*(2) = -1/2 = -0.5.
At point p(x,y), we want d1 = 3d₂, or d₁² = 9d₂².
Therefore
(x + 1)² + (y - 1)² = 9[(x - 2)² + (y + 1)²]
x² + 2x + 1 + y² - 2y + 1 = 9x² - 36x + 36 + 9y² + 18y + 9
8x² - 38x + 8y² + 20y + 43 = 0
x² - 4.75x + y² + 2.5y + 5.375 = 0
(x - 2.375)² - 5.6406 + (y + 1.25)² - 1.5625 + 5.375 = 0
(x - 2.375)² + (y + 1.25)² = 1.828
This is a circle with center at (2.375, -1.25) and radius 1.352.
Answer:
(x - 2.375)² + (y +1.25)² = 1.828