How do you factor the polynomials 3dt-21d+35-5t3dt−21d+35−5t?

1 Answer
EZ as pi
Jan 6, 2017

=(t-7)(3d-5)=(t−7)(3d−5)

Explanation:

The number of terms is a good clue as to the type of factorising which can be done. There is no common factor in all the terms, but we can group them into pairs:

(3dt -21d) + (35-5t)" "larr(3dt−21d)+(35−5t) ← take out common factors

=3d(t-7) color(blue)(+ 5(" "7-t))" "larr=3d(t−7)+5( 7−t) ← do a sign switch round
color(white)(............. .....)darrcolor(white)(.)darrcolor(white)(.)darr
=3d(t-7) color(blue)(- 5(-7+t))

=3d(t-7)- color(blue)(5(t-7))" "larr common bracket

=(t-7)(3d-5)

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