Question

Add the following:

a − b + ab, b − c + bc, c − a + ac

Answer 1

The given expressions are written in separate rows, with like terms one below the other, and then the addition of these expressions is as follows.

a – b + ab
   + b     – c + bc
   –  a    + c        + ac
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          ab + bc + ac

Thus, the sum of the given expressions is ab + bc + ac.