What is #12+ [ - 4+ ( - 9) ]#?

1 Answer
Sep 20, 2016

Answer:

#-1#

Explanation:

Count the number of terms first. Each term simplifies to a single answer and these are added or subtracted in the last line.

#color(blue)(12)+[-4color(red)(+(-9))]" "larr# start with the inner-most brackets.

=#color(blue)(12)+[-4color(red)(-9)]#

=#color(blue)(12)+[color(red)(-13)]#

=#color(blue)(12)color(red)(-13)#

=#-1#

Terms which are already simplified should be carried down to the next line.