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18 Cards in this Set
- Front
- Back
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inverse equation formula
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y=k/x
xy=k |
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what is the constant of variation?
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k
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does this show direct or inverse variation, or neither?
5x-y=3 |
neither
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what is the shape of the graph made by an inverse equation?
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parabola
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when k is negative are the parabolas in quadrant 2 and 3, or 1 and 4?
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1 and 4 (negative)
2 and 3 (positive) |
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To see if a table represents an inverse equation, solve each pair to see if _________________.
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they are all equal
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practice problem-
x=2, y=10 |
10=k/2
k=20 y=20/x |
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what is an excluded value?
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A number subsituted for a variable in the denominator that makes it equal zero (undefined).
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how do you find the excluded value?
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equal the original denominator to zero and solve.
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You can only cross out factors when there is no _________________.
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addition or subtraction
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so can you simplify this?
y ------ 7-y |
nope!
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can you multiply rational expressions straight across? why or why not?
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yes!
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can you divide rational expressions straight across? why or why not?
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nope! Because when you divide fractions, you have to flip the denominator so it becomes the numerator and the numerator becomes the denominator. THEN you can multiply straight across.
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to add and subtract ration expressions, you must ________.
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find the LCD
(don't forget to multiply the numerator by the LCD too!) |
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A boat travels 24 km upstream and 24 km downstream. Write an equation that gives the total time as a function of the boat's average speed in still water. Find the total travel time if the boat's average speed in still water is 10 km per hour. (set up equation)
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t = 24 + 24
---- ----- r-2 r+2 total travel time is 5 hours |
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use cross products to solve
6 = x ---- ---- x+4 2 |
(6)(2)=(x)(x+4)
12=x^2+4x 0=x^2+4x-12 0=(x+6)(x-2) x=-6, 2 |
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d=rt
r=____ t=d/r |
d/t
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work rate x _____ = work done
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time
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