How do I find the square of a binomial?

1 Answer
Elizabeth P.
Oct 20, 2014

Finding the square of a binomial can be done by using the Distributive Property or FOIL. FOIL stands for First, Outer, Inner, Last. There also is a definition in which #(a + b)^2 = a^2 + 2ab + b^2# or #(a - b)^2 = a^2 - 2ab + b^2#

Example:
#(4x + 3)^2#
#(4x + 3)(4x + 3)#

Distributive Property:
#4x(4x + 3) + 3(4x + 3)#
#16x^2 + 12x + 12x + 9#
#16x^2 + 24x + 9# (Proves the #a^2 + 2ab + b^2#)

FOIL:
#(4x + 3)(4x + 3)#
F: 4x4x
O: 4x3
I: 34x
L: 33
#4x*4x + 4x*3 + 3*4x + 3*3#
#16x^2 + 12x + 12x + 9#
#16x^2 + 24x + 9#

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