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Which conjunction or disjunction is equivalent to the open sentence |a – 7| ≤ 5?

a – 7 ≥ 5 or a – 7 ≤ – 5


a – 7 ≤ 5 or a – 7 ≥ – 5


a – 7 ≤ 5 and a – 7 ≥ – 5


a – 7 ≥ 5 and a – 7 ≤ – 5

User Mum
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2 Answers

2 votes

Answer = a - 7 _< 5 and a - 7 >_ - 5

3rd one is correct

or C is correct

User Tinna
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Answer: Choice C

a-7 \le 5 (a-7 is less than or equal to 5)
and

a-7 \ge -5 (a-7 is greater than or equal to -5)

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Step-by-step explanation:


|a-7| \le 5 is the same as
-5 \le a-7 \le 5

We can use the rule that if
|x| \le k then
-k \le x \le k where k is any positive number

After we get
-5 \le a-7 \le 5, we break it down into two pieces. The first piece is
-5 \le a-7 while the second piece is
a-7 \le 5

Flip the two sides of
-5 \le a-7 to get
a-7 \ge -5

So we have
a-7 \le 5 and
a-7 \ge -5

That's why the answer is choice C

Side Note: we must use the connector "and" instead of "or". Both parts of
a-7 \le 5 and
a-7 \ge -5 need to be true, instead of just one part only. This is why we can rule out choice B due to the "or" connector.

User Nakamoto
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