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

1 Answer
Jan 6, 2017

Answer:

#=(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# take out common factors

#=3d(t-7) color(blue)(+ 5(" "7-t))" "larr# 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)#