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3sqrt x =x-4

3 √(x) = x - 4
solve for x​

1 Answer

11 votes

Answer:

x = 16

Explanation:

3√x = x - 4

Raise the equation to the second power.

(3√x)² = (x - 4)²

9x = x² - 8x + 16

Rewrite the equation with the values on the left.

-x² + 17x - 16 = 0

x² - 17x + 16 = 0

Factor.

(x - 16)(x - 1) = 0

Set each part equal to 0.

x - 16 = 0

x = 16

x - 1 = 0

x = 1

Your solutions are 16 and 1, but it doesn't end there. Both of these may not satisfy the original equation, so plug them back in.

3√x = x - 4

3√16 = 16 - 4

3(4) = 12

12 = 2

16 is a solution.

3√x = x - 4

3√1 = 1 - 4

3(1) = -3

3 ≠ -3

1 is NOT a solution.

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