A. Definitions
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number line – a line with numbers that are in a sequential order and differ by the same amount. Zero is called the origin, numbers to the left of zero are negative and numbers to the right of zero are positive.
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integers – positive and negative whole numbers such as {… -3, -2, -1, 0, 1, 2, 3…}.
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opposites – numbers that are the same distance from zero, but on opposite sides of zero,
such as –5 & 5 OR 7 & -7 OR ¾ & -¾.
- When opposites are added, the result is always zero.
- –a is read as the opposite of a.
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absolute value – the distance a number is from zero and distance is always positive.
|-4| = 4, |3| = 3, -|-5| = -5
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velocity - tells how fast an object is moving and in what direction.
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speed - tells only how fast an object is moving. It is the absolute value of velocity provided the object continues to move in a constant direction.
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B. Comparing and Graphing Numbers on the Number Line
- To compare two numbers on the number line, graph them and the one on the left is the smallest, the one on the right is the largest.
- Numbers go smaller to larger from left to right on the number line.
- To graph or plot a number, a darkened circle is put over that number on the number line.
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