math problem?

Question

Perform the operations?
(c+d)(c-d)+d(c-d)


5t(t+5)+(t-1)(t+7)

Answer 1

I used the FOIL method (First, Outer, Inner, Last) to get:

c^2 +cd -2d^2

6t^2 +31t -7

I haven't done this in years so you might want to check. (^2 = squared)

Answer 2

5t^2 + 25t + t^2 + 6t - 7
6t^2 + 31t - 7 is the final answer

6t is recieved from 7t and -t combined.

Tell me if you have any problems with it

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Answer 3

c^2-d^2+dc=d^2
5t^2+25t+t^2+6t-7