factor completely.\n$(x^{2}-5x + 4)(x^{2}-9)=$

Explanation:

Step1: Factor $x^{2}-5x + 4$

We find two numbers that multiply to $4$ and add up to $-5$. They are $-4$ and $-1$. So $x^{2}-5x + 4=(x - 4)(x - 1)$.

Step2: Factor $x^{2}-9$

Using the difference - of - squares formula $a^{2}-b^{2}=(a + b)(a - b)$ with $a=x$ and $b = 3$, we get $x^{2}-9=(x + 3)(x - 3)$.

Step3: Combine the factors

$(x^{2}-5x + 4)(x^{2}-9)=(x - 4)(x - 1)(x + 3)(x - 3)$

Answer:

$(x - 4)(x - 1)(x + 3)(x - 3)$