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The additive
inverse of a number is the number that when added with the first,
results in zero. |
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For example,
the additive inverse of 5 is
negative 5 (-5), because 5 + (-5) = 0 |
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The additive
inverse of 3 is -3, because
3 + (-3) = 0 |
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Another name
for additive inverse is "opposite". So the "opposite" of 4 is
-4. |
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Another way to think of
"opposites" is to visualize a number line. "Opposites"
are an equal distance from zero, and therefore their sum is 0. |
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You can see
from the above number line that both 3 and (-3) are three units from
zero, therefore they are equal distances from zero, and
3 + (-3) = 0 |
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Why do you need to know
additive inverses? Where do you use it in mathematics?
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One place you use them
is when solving equations; e.g. to solve x + 3 = 9 |
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x + 3 = 9
(you need x by itself; you need to "move" the 3)
x + 3 + -3 = 9 +
-3 (add the opposite of 3
to each side)
x + 0 = 6
(a number plus its opposite equals 0)
x = 6 |
Ready to
practice this skill?
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