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sveta [45]
3 years ago
15

Prove that if xy > 0, then either x > 0 and y > 0 or x < 0 and y < 0

Mathematics
1 answer:
Rufina [12.5K]3 years ago
7 0

The rule of product states that:

  • (+) \cdot (+) = (+)
  • (+) \cdot (-) = (-)
  • (-) \cdot (+) = (-)
  • (-) \cdot (-) = (+)

So, a product is positive if and only if both factors have the same sign, and is negative if only if the factors have opposite sign.

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125,600 surface area converted to volume?
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Answer:

1256000

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My example:

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Multiply each side of the equation by 3 and the equation becomes: 13.5 ? cubic feet =4?(r^3)

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Use the calculator to find the cubic root of 3.38 and subsequently the value of the radius “r” in feet. Find the function key designated for cubic roots, press this key and then enter the value 3.38. You find that the radius is 1.50 ft. You can also use an online calculator for this calculation (see the Resources).

Substitute 1.50 ft. in the formula for SA= 4?(r^2) found in Step 1. To find: SA = 4?(1.50^2) = 4?(1.50X1.50) is equal to 9? square ft.

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8 0
3 years ago
the length of a flag is 0.3 foot less than twice its width. if the perimeter is 14.4 feet longer than the width, find the dimens
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x-\ length\\&#10;y-\ width\\\\&#10;x+0.3=2y\ \ \ \ \ | subtract\ 0.3\\x=2y-0.3\\&#10;perimeter=2x+2y\\ 2x+2y-14.4=y\\\\&#10;2*(2y-0.3)+2y-14.4=y\\&#10;4y-0.6+2y-14.4=y\\&#10;6y-15=y\ \ \ | add\ 15\\&#10;6y=15+y\ \ | subtract\ y\\&#10;5y=15\ \ \ | divide\ by\ 5\\&#10;y=3\\&#10;x=2y-0.3=2*3-0.3=6-0.3=5.7\\\\&#10;Dimensions:\ length=5.7\ feet\, width=3\ feet.
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4 years ago
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