How do you multiply #(5k-5)(k^2-4k-5)#?

2 Answers
Jun 30, 2017

Answer:

See a solution process below:

Explanation:

To multiply these two terms you multiply each individual term in the left parenthesis by each individual term in the right parenthesis.

#(color(red)(5k) - color(red)(5))(color(blue)(k^2) - color(blue)(4k) - color(blue)(5))# becomes:

#(color(red)(5k) xx color(blue)(k^2)) - (color(red)(5k) xx color(blue)(4k)) - (color(red)(5k) xx color(blue)(5)) - (color(red)(5) xx color(blue)(k^2)) + (color(red)(5) xx color(blue)(4k)) + (color(red)(5) xx color(blue)(5))#

#5k^3 - 20k^2 -25k - 5k^2 + 20k + 25#

We can now group and combine like terms:

#5k^3 - 20k^2 - 5k^2 -25k + 20k + 25#

#5k^3 + (-20 - 5)k^2 + (-25 + 20)k + 25#

#5k^3 + (-25)k^2 + (-5)k + 25#

#5k^3 - 25k^2 - 5k + 25#

Jun 30, 2017

Answer:

#color(green)(5k^3-25k^2-5k+25#

Explanation:

#color(white)(aaaaaaaaaaaaa)##k^2-4k-5#
#color(white)(aaaaaaaaaaa)## xx underline(5k-5)#
#color(white)(aaaaaaaaaaaaa)##5k^3-20k^2-25k#
#color(white)(aaaaaaaaaaaaaaaaa)##-5k^2+20k+25#
#color(white)(aaaaaaaaaaaaa)##overline(5k^3-25k^2-5k+25)#

#color(white)(aaaaaaaaaaaaa)##color(green)(5k^3-25k^2-5k+25#