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jmc

algebra senior

Problem

Find the sum of all integers that satisfy these conditions:
Solution
First, let's deal with . Subtracting 1 from both sides gives , so the integers that satisfy are those greater than 6 and those less than . Since the inequality is strict (, not ), cannot be 6 or .

Next, we consider . Writing this as , we see that must be within of on the number line, which means it must be one of the integers from to 6. Since the inequality is nonstrict (, not ), can be or 6.

The only integers that satisfy both inequalities are and , and their sum is .
Final answer
-15