According to the fundamental theorem of algebra, every polynomial of degree n has n complex zeroes.
Part A:
Given
[tex]x(x^2-4)(x^2+16)=0 \\ \\ \Rightarrow x(x^4+12x^2-64)=0 \\ \\ \Rightarrow x^5+12x^3-64x=0[/tex]
Thus, the given polynomial is of degree 5 and hence has 5 omplrex roots.
Part B:
Given
[tex](x^2+4)(x+5)^2 = 0 \\ \\ \Rightarrow(x^2+4)(x^2+10x+25)=0 \\ \\ \Rightarrow x^4+10x^3+25x^2+4x^2+40x+100=0 \\ \\ \Rightarrow x^4+10x^3+29x^2+40x+100=0[/tex]
Thus, the polynomial is of degree 4 and hence has 4 complex roots.
Part C:
Given
[tex]x^6-4x^5-24x^2+10x-3=0[/tex]
Thus, the given polynomial is of degree 6 and hence has 6 complex roots.
Part D:
Given
[tex]x^7+128=0[/tex]
Thus, the given polynomial is of degree 7 and hence has 7 complex roots.
Part E:
Given
[tex](x^3+9)(x^2-4)=0 \\ \\ \Rightarrow x^5-4x^3+9x^2-36=0[/tex]
Thus, the given polynomial is of degree 5 and hence has 5 complex roots.