Question

Does anyone have the answer key to these proofs? They are Mrs. E Teaches Math introductory proofs. There are 14 total. I've done 1-9.​

Answer 1

Statement 1:  2AB = AC

Reason 1: Given

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Statement 2:  AC = AB+BC

Reason 2: Segment addition postulate (which your teacher abbreviated to "Seg + Post")

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Statement 3: 2AB = AB+BC

Reason 3: Substitution

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Statement 4:  2AB-AB = AB+BC-AB

Reason 4: Subtraction Property of Equality

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Statement 5: AB = BC

Reason 5: Combine like terms

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Notes:

• The first reason is "given" since we just simply restate what the instructions provide. If you are given multiple items, you list each one at a time.
• The segment addition postulate is where we break a line into smaller parts and then build it back together.
• Substitution is simply replacement. We've replaced AC with 2AB.
• The subtraction property of equality is the idea where we subtract the same thing from both sides. In statement 4, we're subtracting AB from both sides.
• The last statement of any proof is always the thing we're trying to prove. Once we reach such a statement, there's no need to go any further since the proof has concluded.