Multiplying by a negative number is just a quick way of moving things to the other side of the inequality. Consider
-2x < 100
Now, you could solve it without doing any negative multiplying at all: just add 2x to both sides to get
0 < 2x + 100
Now subtract the 100 to get
-100 < 2x
or,
2x > -100
changing the sense of the inequality just means that terms have switched sides in the expression as written.
Why does the inequality sign change when both sides are multiplied or divided by a negative number? Does this happen with equations? Explain
2 answers
thank you!