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The real roots of the equation x^(2//3)+...

The real roots of the equation `x^(2//3)+x^(1//3)-2=0` are

A

1,8

B

`-1,-8`

C

`-1,8`

D

`1,-8`

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The correct Answer is:
To solve the equation \( x^{2/3} + x^{1/3} - 2 = 0 \) for its real roots, we can follow these steps: ### Step 1: Substitute \( y = x^{1/3} \) Let \( y = x^{1/3} \). Then, we can express \( x^{2/3} \) as \( y^2 \). The equation becomes: \[ y^2 + y - 2 = 0 \] ### Step 2: Factor the quadratic equation Next, we need to factor the quadratic equation \( y^2 + y - 2 = 0 \). We look for two numbers that multiply to \(-2\) and add to \(1\). The numbers \(2\) and \(-1\) fit this requirement. Thus, we can factor the equation as: \[ (y - 1)(y + 2) = 0 \] ### Step 3: Solve for \( y \) Setting each factor to zero gives us: 1. \( y - 1 = 0 \) → \( y = 1 \) 2. \( y + 2 = 0 \) → \( y = -2 \) ### Step 4: Substitute back to find \( x \) Now, we substitute back for \( y \): 1. For \( y = 1 \): \[ x^{1/3} = 1 \implies x = 1^3 = 1 \] 2. For \( y = -2 \): \[ x^{1/3} = -2 \implies x = (-2)^3 = -8 \] ### Step 5: List the real roots The real roots of the original equation \( x^{2/3} + x^{1/3} - 2 = 0 \) are: \[ x = 1 \quad \text{and} \quad x = -8 \] ### Final Answer: The real roots of the equation are \( x = 1 \) and \( x = -8 \). ---
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