Answers

2014-08-12T21:27:14+08:00
=6-f \\ 4-f × f+4 \\ f+6

=-f+6 \\ -f+4 × f+4 \\ f+6

=(-1)(f+6) \\ (-1)(f+4) × f+4 \\ f+6

*Cancel out all the (f+6) and all (f+4)*

=-1 \\ -1

=1
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