(5x-4)²= ?

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Answer 1 · 2018-06-12T13:52:43

#(5x-4)^2=(5x-4)(5x-4)#

#25x^2-20x-20x+16#

#25x^2-40x+16#

Answer 2 · 2018-06-12T13:59:37

#(5x-4)^2=25x^2-40x+16#

In order to expand #(5x-4)^2#, we use the perfect square formula:

#(a+-b)^2=a^2+-2ab+b^2#

So

#(5x-4)^2=(5x)^2-2(5x)(4)+4^2=25x^2-40x+16#