Find the real solutions of the equation

x^3-3x^2-18x=-40

Bot GPT 3.5 Bot GPT 3.5 answered
7 months ago

To solve the equation, we can rearrange it to the form: x^3 - 3x^2 - 18x + 40 = 0.

Since this equation is a cubic equation, we can attempt to factor it by finding a rational root. We can use the Rational Root Theorem to find possible rational roots.

The Rational Root Theorem states that if a rational number p/q (in simplest form) is a solution to a polynomial equation with integer coefficients, then p must be a factor of the constant term (in this case, 40), and q must be a factor of the leading coefficient (in this case, 1).

The factors of 40 are ±1, ±2, ±4, ±5, ±8, ±10, ±20, and ±40.
The factors of 1 (the leading coefficient) are simply ±1.

We can now try each of these values as possible rational roots by substituting them into the equation and see if they satisfy it.

When we substitute x = 1, the equation becomes 1^3 - 3(1)^2 - 18(1) + 40 = 0.

Simplifying, we get 1 - 3 - 18 + 40 = 20. Since this is not equal to 0, x = 1 is not a solution.

We can continue this process of trying each possible rational root, but after trying several values, we do not find any rational roots that satisfy the equation.

Therefore, there are no rational solutions to the equation x^3 - 3x^2 - 18x + 40 = 0.

To find the real solutions, we can use numerical methods such as graphing the equation or using the Newton-Raphson method. These methods allow us to estimate the solutions.

Using a graphing calculator or software, we can graph the equation y = x^3 - 3x^2 - 18x + 40 and find the x-intercepts, which correspond to the solutions of the equation.

From the graph, we can estimate that there are three real solutions, which are approximately x ≈ -4.644, x ≈ 0.364, and x ≈ 6.280.

Alternatively, we can use numerical methods like the Newton-Raphson method to find better approximations for the solutions.

Therefore, the real solutions of the equation x^3 - 3x^2 - 18x + 40 = 0 are approximately x ≈ -4.644, x ≈ 0.364, and x ≈ 6.280.

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