How do you multiply #(-1 + 5a)^2#?

1 Answer
MeneerNask
Jul 8, 2016

There are two ways: you use the special products rule, or you write out the square into #(-1+5a)(-1+5a)#

Explanation:

Special products:
#(A+B)^2=A^2+2AB+B^2# where #A=-1 and B=5a#
#=(-1)^2+2*(-1)*5a+(5a)^2#
#=1-10a+25a^2#

Writing out the square and FOIL:
#=(-1)xx(-1)+(-1)xx(5a)+(5a)xx(-1)+(5a)xx(5a)#
#=1-5a-5a+25a^2#

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