How do you multiply #(5x + 4) ( 5x + 5) ( 2x - 6) ( x - 4)#?

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Answer 1 · 2018-01-13T05:46:37

#50x^4-260x^3+10x^2+800x+480#

Just use repeated expansion.

#(5x+4)(5x+5)(2x-6)(x-4)#

#(25x^2+25x+20x+20)(2x-6)(x-4)#

#(25x^2+45x+20)(2x-6)(x-4)#

Factor out #2x-6=2(x-3)#, we get

#2(25x^2+45x+20)(x-3)(x-4)#

#(50x^2+90x+40)(x-3)(x-4)#

#(50x^3-150x^2+90x^2-270x+40x-120)(x-4)#

#(50x^3-60x^2-230x-120)(x-4)#

#(50x^4-200x^3-60x^3+240x^2-230x^2+920x-120x+480)#

#50x^4-260x^3+10x^2+800x+480#