Rewrite the given polynomial equation by completing the square.

[tex]\[
\begin{array}{l}
x^4 + 18x^2 + 81 = (\quad)^2 + 2\left(\quad x^2 + (\quad)^2\right) \\
x^4 + 18x^2 + 81 = (\quad)^2
\end{array}
\][/tex]

Complete the square for the given expression.

[tex]\[x^2 + 9 \quad x^2 - 9\][/tex]

Simplify the components.

[tex]\[x^2\][/tex]
[tex]\[3^2\][/tex]
[tex]\[3\][/tex]
[tex]\[81\][/tex]



Answer :

To solve the polynomial equation provided, let's break down the steps one-by-one to reach the solution.

Given the equation:
[tex]\[ x^4 + 18x^2 + 81 \][/tex]

First, observe that you can rewrite the polynomial in a way that will reveal its structure more clearly.

1. Identify the structure of the polynomial:

[tex]\[ x^4 + 18x^2 + 81 \][/tex]

If we consider [tex]\( x^2 \)[/tex] as a single term, this polynomial resembles the form of a quadratic equation:
[tex]\[ (x^2)^2 + 18(x^2) + 81 \][/tex]

2. Rewrite the equation in a perfect square form:

Notice that [tex]\( x^4 + 18x^2 + 81 \)[/tex] looks similar to the structure of a perfect square trinomial. A perfect square trinomial follows the form:
[tex]\[ (a + b)^2 = a^2 + 2ab + b^2 \][/tex]

By recognizing this form, we can express the original polynomial as a square of a binomial.

3. Find the suitable binomial:

Let's express the given polynomial as:
[tex]\[ x^4 + 18x^2 + 81 = (x^2 + 9)^2 \][/tex]

Here, we see:

- [tex]\( a = x^2 \)[/tex]
- [tex]\( b = 9 \)[/tex]

Using this combination:
[tex]\[ (x^2 + 9)^2 \][/tex]

4. Verify the expanded form:

To ensure correctness, let's expand [tex]\( (x^2 + 9)^2 \)[/tex]:

[tex]\[ (x^2 + 9)^2 = (x^2 + 9)(x^2 + 9) \][/tex]

Expanding this:
[tex]\[ (x^2 + 9)(x^2 + 9) = x^4 + 9x^2 + 9x^2 + 81 \][/tex]
[tex]\[ = x^4 + 18x^2 + 81 \][/tex]

Thus, we can confirm that:
[tex]\[ x^4 + 18x^2 + 81 = (x^2 + 9)^2 \][/tex]

5. Result:

Finally, the polynomial [tex]\( x^4 + 18x^2 + 81 \)[/tex] can be rewritten as a perfect square:
[tex]\[ (x^2 + 9)^2 \][/tex]

6. Simplification:

Simplifying, we state:
[tex]\[ x^2 + 9 \][/tex]

Therefore, the detailed solution is:

[tex]\[ x^4 + 18x^2 + 81 = (x^2 + 9)^2 \][/tex]

And the simplified expression is:
[tex]\[ x^2 + 9 \][/tex]