Algebra Examples

$x^{\frac{2}{3}} - x^{\frac{1}{3}} - 6 = 0$

Step 1

Factor the left side of the equation.

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Step 1.1

Rewrite $x^{\frac{2}{3}}$ as ${(x^{\frac{1}{3}})}^{2}$ .

${(x^{\frac{1}{3}})}^{2} - x^{\frac{1}{3}} - 6 = 0$

Step 1.2

Let $u = x^{\frac{1}{3}}$ . Substitute $u$ for all occurrences of $x^{\frac{1}{3}}$ .

$u^{2} - u - 6 = 0$

Step 1.3

Factor $u^{2} - u - 6$ using the AC method.

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Step 1.3.1

Consider the form $x^{2} + b x + c$ . Find a pair of integers whose product is $c$ and whose sum is $b$ . In this case, whose product is $- 6$ and whose sum is $- 1$ .

$- 3, 2$

Step 1.3.2

Write the factored form using these integers.

$(u - 3) (u + 2) = 0$

Step 1.4

Replace all occurrences of $u$ with $x^{\frac{1}{3}}$ .

$(x^{\frac{1}{3}} - 3) (x^{\frac{1}{3}} + 2) = 0$

Step 2

If any individual factor on the left side of the equation is equal to $0$ , the entire expression will be equal to $0$ .

$x^{\frac{1}{3}} - 3 = 0$

$x^{\frac{1}{3}} + 2 = 0$

Step 3

Set $x^{\frac{1}{3}} - 3$ equal to $0$ and solve for $x$ .

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Step 3.1

Set $x^{\frac{1}{3}} - 3$ equal to $0$ .

$x^{\frac{1}{3}} - 3 = 0$

Step 3.2

Solve $x^{\frac{1}{3}} - 3 = 0$ for $x$ .

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Step 3.2.1

Add $3$ to both sides of the equation.

$x^{\frac{1}{3}} = 3$

Step 3.2.2

Raise each side of the equation to the power of $3$ to eliminate the fractional exponent on the left side.

${(x^{\frac{1}{3}})}^{3} = 3^{3}$

Step 3.2.3

Simplify the exponent.

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Step 3.2.3.1

Simplify the left side.

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Step 3.2.3.1.1

Simplify ${(x^{\frac{1}{3}})}^{3}$ .

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Step 3.2.3.1.1.1

Multiply the exponents in ${(x^{\frac{1}{3}})}^{3}$ .

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Step 3.2.3.1.1.1.1

Apply the power rule and multiply exponents, ${(a^{m})}^{n} = a^{m n}$ .

$x^{\frac{1}{3} \cdot 3} = 3^{3}$

Step 3.2.3.1.1.1.2

Cancel the common factor of $3$ .

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Step 3.2.3.1.1.1.2.1

Cancel the common factor.

$x^{\frac{1}{3} \cdot 3} = 3^{3}$

Step 3.2.3.1.1.1.2.2

Rewrite the expression.

$x^{1} = 3^{3}$

Step 3.2.3.1.1.2

Simplify.

$x = 3^{3}$

Step 3.2.3.2

Simplify the right side.

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Step 3.2.3.2.1

Raise $3$ to the power of $3$ .

$x = 27$

Step 4

Set $x^{\frac{1}{3}} + 2$ equal to $0$ and solve for $x$ .

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Step 4.1

Set $x^{\frac{1}{3}} + 2$ equal to $0$ .

$x^{\frac{1}{3}} + 2 = 0$

Step 4.2

Solve $x^{\frac{1}{3}} + 2 = 0$ for $x$ .

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Step 4.2.1

Subtract $2$ from both sides of the equation.

$x^{\frac{1}{3}} = - 2$

Step 4.2.2

Raise each side of the equation to the power of $3$ to eliminate the fractional exponent on the left side.

${(x^{\frac{1}{3}})}^{3} = {(- 2)}^{3}$

Step 4.2.3

Simplify the exponent.

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Step 4.2.3.1

Simplify the left side.

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Step 4.2.3.1.1

Simplify ${(x^{\frac{1}{3}})}^{3}$ .

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Step 4.2.3.1.1.1

Multiply the exponents in ${(x^{\frac{1}{3}})}^{3}$ .

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Step 4.2.3.1.1.1.1

Apply the power rule and multiply exponents, ${(a^{m})}^{n} = a^{m n}$ .

$x^{\frac{1}{3} \cdot 3} = {(- 2)}^{3}$

Step 4.2.3.1.1.1.2

Cancel the common factor of $3$ .

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Step 4.2.3.1.1.1.2.1

Cancel the common factor.

$x^{\frac{1}{3} \cdot 3} = {(- 2)}^{3}$

Step 4.2.3.1.1.1.2.2

Rewrite the expression.

$x^{1} = {(- 2)}^{3}$

Step 4.2.3.1.1.2

Simplify.

$x = {(- 2)}^{3}$

Step 4.2.3.2

Simplify the right side.

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Step 4.2.3.2.1

Raise $- 2$ to the power of $3$ .

$x = - 8$

Step 5

The final solution is all the values that make $(x^{\frac{1}{3}} - 3) (x^{\frac{1}{3}} + 2) = 0$ true.

$x = 27, - 8$