Reasoning with Equations and Inequalities

Solving an Inequality

What’s the mistake, and how would you move this student forward to a complete understanding of how to solve inequalities?

One reply on “Solving an Inequality”

Because 1 is always easy, I’d have the student try -1 in the original expression, then do the comparison. I’d do the same with -10d. Then I’d try +1. Then, if we had to, I’d do +2 and then I’d talk about adding 10d to both sides of the inequality and what happens to d.
I did like that this student knew that 0 was not an option.

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