Anonymous
Anonymous asked in Education & ReferenceHomework Help · 8 months ago

# I got true for the question but the answer is false can someone please explain why its false? (A − C) − (B − C) = A − B.?

Update:

For this question I drew Venn diagrams for both sides to see if they matched and they didn't. I was told to use a membership table to see why its false. I know membership tables are like truth tables, but how do you make a membership table when there are subtraction signs in the question?

Update 2:

CORRECTION: Sorry I meant I got false for the answer and the correct answer is TRUE.

Relevance

Remove the brackets...

A - C - B + C

= A - B

YOU are correct.... their answer is wrong.

• Yes, you always have to remove the brackets before you simplify...thanks for BA 👍

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• Anonymous
8 months ago

Two negatives make a positive so - (-C) is +C.

Then A - C - B + C and the C's cancel out.

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• Order of operation.  You do the stuff in parentheses first, THEN the rest.  Using (this is just an example) A=5, B=4, and C=1, doing it correctly, the answer would reduce to 1.  Doing it like A-C-B-C will yield -1.

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