How do you FOIL #(x-10)(x+10)#?

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Answer 1 · 2018-03-05T05:52:58

#x^2-100#

FOIL stands for First, Outside, Inside, Last

multiply the First terms
#x*x=x^2#

multiply the Outside terms
#x*10=10x#

multiply the Inside terms
#-10*x=-10x#

multiply the Last terms
#-10*10=-100#

add all of the answers together
#x^2+10x-10x-100#

combine like terms
#x^2+color(red)(10x-10x)-100#
#=x^2-100#