Math CentralQuandaries & Queries


Question from jimmy, a student:

1.7b-1.1 <2.3

Hi Jimmy.

Here at Math Central we try to teach students how to understand math, so I will demonstrate how to solve a similar question to yours. If you are simply looking for an answer without learning how to figure things out, you may prefer to simply punch such a question into a calculator such as Wolfram Alpha.

My example question is this:

Simplify 2.4 - 0.3x > -3.6

To solve "inequalities" you can use almost the exact same steps for normal equations, except that multiplying or dividing by a negative on both sides leads to reversing the direction of the inequality.

Thus, I first subtract 2.4 from each side in order to get closer to having x isolated by itself on one side:

(2.4 - 0.3x) - 2.4 > (-3.6) - 2.4

- 0.3x > - 6.0

Now, to finish isolating x, I need to divide both sides by -0.3. Since this is a negative number, I need to flip the direction of the inequality:

(-0.3x) / (-0.3) < (-6.0) / (-0.3)

x < 20

This is the simplified answer to the example question.

I hope you find this helpful in solving your own question.
Stephen La Rocque.

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