SOLUTION: why does the inequality sign change when both sides are multiplied by a negative number. Does this happen with equations, why or why not?

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Question 606090: why does the inequality sign change when both sides are multiplied by a negative number. Does this happen with equations, why or why not?

Found 2 solutions by richard1234, stanbon:
Answer by richard1234(7193) About Me  (Show Source):
You can put this solution on YOUR website!
Suppose . Subtracting a+b from both sides does not change the inequality sign:





For example, 3 < 7 but -3 > -7. This does not happen with equations (you can't "flip" an equal sign as you flip an inequality sign).

Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
why does the inequality sign change when both sides are multiplied by a negative number.
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2 < 3 means 3 is to the right of 2 on the number scale.
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Multiplying by -1 flips the relationship of the numbers over
the y-axis so -3 is to the left of -2, i.e. -3 < -2
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Does this happen with equations, why or why not?
No; 2 = 2 and -2=-2

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Cheers,
Stan H.
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