College

Solve the equation [tex]25x^3 + 25x^2 - x - 1 = 0[/tex] given that [tex]x = -10[/tex] is a zero of [tex]f(x) = 25x^3 + 25x^2 - x - 1[/tex].

Answer :

the given equation has three solutions: x = -10, 1.292, 8.476, 1.046.

To solve the equation 25x³ + 25x² - x - 1 = 0, we are given that -10 is a zero of the function f(x) = 25x³ + 25x² - x - 1.

To find the remaining solutions, we can use polynomial division or synthetic division to divide the polynomial by (x + 10) since -10 is a zero.

Performing the synthetic division:

-10 | 25 25 -1 -1

| -250 0 10 -90

|-----------------------------

0 -225 9 -91

The resulting quotient is 25x² - 225x + 9 with a remainder of -91.

Now we have a quadratic equation: 25x² - 225x + 9 = 0

We can solve this quadratic equation using the quadratic formula:

x = (-b ± √(b² - 4ac)) / (2a)

For our quadratic equation, a = 25, b = -225, and c = 9.

Using the quadratic formula, we can calculate the remaining solutions for x:

x = (-(-225) ± √((-225)² - 4(25)(9))) / (2(25))

x = (225 ± √(50625 - 900)) / 50

x = (225 ± √49725) / 50

x ≈ (225 ± 223.17) / 50

So the remaining solutions are:

x ≈ (225 + 223.17) / 50 ≈ 8.476

x ≈ (225 - 223.17) / 50 ≈ 1.046

Therefore, the solutions to the equation 25x³ + 25x² - x - 1 = 0 are approximately:

x = -10, 1.292, 8.476, 1.046.

Final answer:

To solve the equation 25x³ + 25x² - x - 1 = 0, we can use polynomial long division or synthetic division to find the other solutions after given one solution. The solutions include a real number and two complex numbers.


Explanation:

To solve the equation 25x³ + 25x² - x - 1 = 0, we are given that -10 is a zero of the equation. This means that when x = -10, the equation becomes zero. To find the other solutions, we can use polynomial long division or synthetic division to divide the equation by (x - (-10)) or (x + 10). By doing this, we obtain a quadratic equation that we can solve using factoring, the quadratic formula, or completing the square.

The division gives us a quotient of 25x² + 250x + 249. Setting this quotient equal to zero and solving for x, we find that the remaining solutions are not real numbers but complex numbers. So, the solutions to the equation 25x³ + 25x² - x - 1 = 0 are x = -10 and two complex numbers.


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