Answer:
The factors are
[tex]\text{A. } x^2 + 9[/tex]
[tex]\text{D. } x + 3[/tex]
Step-by-step explanation:
[tex]x^4- 81[/tex]
[tex](x^2)^2-9^2[/tex]
Once [tex]x^2-y^2=\left(x+y\right)\left(x-y\right)[/tex]
[tex]\left(x^2\right)^2-9^2 = \left(x^2+9\right)\left(x^2-9\right)[/tex]
Now we can factor [tex]x^2-9[/tex] again using difference of two squares:
Therefore,
[tex]\left(x^2+9\right)\left(x+3\right)\left(x-3\right)[/tex]
The factors are
[tex]\text{A. } x^2 + 9[/tex]
[tex]\text{D. } x + 3[/tex]
