Solving Cubic Equation: 9(x-1)³ = -125/27
To solve the equation 9(x-1)ᄈ = -125/27, we can start by simplifying the left side using the cube of a binomial formula:
(x-1)ᄈ = (x)ᄈ - 3(x)ᄇ(1) + 3(x)(1)ᄇ - 1ᄈ = xᄈ - 3xᄇ + 3x - 1
Substituting back into the original equation, we have:
9(xᄈ - 3xᄇ + 3x - 1) = -125/27
Expanding and simplifying:
9xᄈ - 27xᄇ + 27x - 9 = -125/27
Multiplying both sides by 27 to get rid of the fraction:
243xᄈ - 729xᄇ + 729x - 243 = -125
Adding 125 to both sides:
243xᄈ - 729xᄇ + 729x - 118 = 0
Dividing both sides by 9 to simplify:
27xᄈ - 81xᄇ + 81x - 13 = 0
We can use synthetic division or a factor theorem to check that x = 1/3 is a root of this equation. Dividing by (x - 1/3), we get:
27xᄇ - 54x + 39 = 0
This quadratic equation has no real solutions, so the only solution to the original equation is x = 1/3.
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