Question 1063520
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solve by factoring given that (x+4) is one factor

x^3+4x^2-16x-64=0
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I can easily do it without this hint, simply applying grouping:


{{{x^3 + 4x^2 - 16x - 64}}} = {{{(x^3 + 4x^2)}}} + {{{(- 16x - 64)}}} = {{{x^2(x+4)}}} - {{{16*(x+4)}}} = {{{(x+4)*(x^2-16)}}} = {{{(x+4)*(X+4)*(x-4)}}} = {{{(x+4)^2*(x-4)}}}.


Hence, the original equation has the root x = -4 of multiplicity 2 and the root x = 4.