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What are the roots of the polynomial equation [tex]x^4 + x^3 = 4x^2 + 4x[/tex]?

A. [tex]\(-2, -1, 0, 2\)[/tex]
B. [tex]\(-2, 0, 1, 2\)[/tex]
C. [tex]\(-1, 0\)[/tex]
D. [tex]\(0, 1\)[/tex]


Sagot :

To find the roots of the polynomial equation [tex]\(x^4 + x^3 = 4x^2 + 4x\)[/tex], we will systematically solve it step by step.

1. Rewrite the equation:
Start with the given polynomial equation:
[tex]\[ x^4 + x^3 = 4x^2 + 4x \][/tex]

2. Bring all terms to one side:
To facilitate solving, we move all terms to one side of the equation:
[tex]\[ x^4 + x^3 - 4x^2 - 4x = 0 \][/tex]

3. Factor the polynomial:
To solve for [tex]\( x \)[/tex], we can try to factor the polynomial. Notice that all terms have a common factor, which is [tex]\( x \)[/tex]:
[tex]\[ x(x^3 + x^2 - 4x - 4) = 0 \][/tex]

This gives us one root directly:
[tex]\[ x = 0 \][/tex]

4. Solve the remaining polynomial:
Now, we need to solve the cubic equation:
[tex]\[ x^3 + x^2 - 4x - 4 = 0 \][/tex]

Through further factoring or using methods such as the Rational Root Theorem, we can find that the factors of this polynomial include [tex]\( (x + 2) \)[/tex], [tex]\( (x + 1) \)[/tex], and [tex]\( (x - 2) \)[/tex].

This means we can write:
[tex]\[ x^3 + x^2 - 4x - 4 = (x + 2)(x + 1)(x - 2) \][/tex]

5. Find the remaining roots:
Solve for [tex]\( x \)[/tex] from the factored form:
[tex]\[ (x + 2) = 0 \quad \Rightarrow \quad x = -2 \][/tex]
[tex]\[ (x + 1) = 0 \quad \Rightarrow \quad x = -1 \][/tex]
[tex]\[ (x - 2) = 0 \quad \Rightarrow \quad x = 2 \][/tex]

6. Collect all roots:
Combining these solutions, we get the roots of the polynomial equation [tex]\( x^4 + x^3 = 4x^2 + 4x \)[/tex]:
[tex]\[ x = -2, -1, 0, 2 \][/tex]

Therefore, the roots of the given equation [tex]\( x^4 + x^3 = 4x^2 + 4x \)[/tex] are:
[tex]\[ \boxed{-2, -1, 0, 2} \][/tex]