How do you find the zeros of #x^3+x^2-4x-4#?
1 Answer
Aug 19, 2016
This cubic has zeros:
Explanation:
This cubic factors by grouping then using the difference of squares identity:
#a^2-b^2=(a-b)(a+b)#
with
#x^3+x^2-4x-4#
#=(x^3+x^2)-(4x+4)#
#=x^2(x+1)-4(x+1)#
#=(x^2-4)(x+1)#
#=(x^2-2^2)(x+1)#
#=(x-2)(x+2)(x+1)#
Hence zeros:
#2, -2, -1#
