Cubic equations

Mathematics

ScanSolve AI Answer

Answer

x=1,x=3,x=−2x=1, x=3, x=-2

x=1,x=2,x=3x=1, x=2, x=3

Step-by-step solution

8 steps

Here are the solutions for the cubic equations:

1) Solve x3−2x2−5x+6=0x^3 - 2x^2 - 5x + 6 = 0

  1. Find possible rational roots using the Rational Root Theorem.

    The constant term is 6, and the leading coefficient is 1. Possible rational roots are the divisors of 6: ±1,±2,±3,±6\pm 1, \pm 2, \pm 3, \pm 6.

  2. Test for a root using substitution or synthetic division.

    Let P(x)=x3−2x2−5x+6P(x) = x^3 - 2x^2 - 5x + 6.
    Test x=1x=1:

    P(1)=(1)3−2(1)2−5(1)+6=1−2−5+6=0P(1) = (1)^3 - 2(1)^2 - 5(1) + 6 = 1 - 2 - 5 + 6 = 0

    Since P(1)=0P(1)=0, x=1x=1 is a root, and (x−1)(x-1) is a factor.

  3. Use synthetic division to find the depressed quadratic equation.

    Dividing x3−2x2−5x+6x^3 - 2x^2 - 5x + 6 by (x−1)(x-1):

    1 | 1  -2  -5   6
      |    1  -1  -6
      ----------------
        1  -1  -6   0
    

    The resulting quadratic equation is x2−x−6=0x^2 - x - 6 = 0.

  4. Solve the quadratic equation.

    Factor the quadratic equation:

    (x−3)(x+2)=0(x-3)(x+2) = 0

    This gives the roots x=3x=3 and x=−2x=-2.

    The solutions for the equation x3−2x2−5x+6=0x^3 - 2x^2 - 5x + 6 = 0 are: x=1,x=3,x=−2\boxed{x=1, x=3, x=-2}

    2) Solve x3−6x2+11x−6=0x^3 - 6x^2 + 11x - 6 = 0

  5. Find possible rational roots using the Rational Root Theorem.

    The constant term is -6, and the leading coefficient is 1. Possible rational roots are the divisors of -6: ±1,±2,±3,±6\pm 1, \pm 2, \pm 3, \pm 6.

  6. Test for a root using substitution or synthetic division.

    Let P(x)=x3−6x2+11x−6P(x) = x^3 - 6x^2 + 11x - 6.
    Test x=1x=1:

    P(1)=(1)3−6(1)2+11(1)−6=1−6+11−6=0P(1) = (1)^3 - 6(1)^2 + 11(1) - 6 = 1 - 6 + 11 - 6 = 0

    Since P(1)=0P(1)=0, x=1x=1 is a root, and (x−1)(x-1) is a factor.

  7. Use synthetic division to find the depressed quadratic equation.

    Dividing x3−6x2+11x−6x^3 - 6x^2 + 11x - 6 by (x−1)(x-1):

    1 | 1  -6   11  -6
      |    1  -5    6
      ----------------
        1  -5    6   0
    

    The resulting quadratic equation is x2−5x+6=0x^2 - 5x + 6 = 0.

  8. Solve the quadratic equation.

    Factor the quadratic equation:

    (x−2)(x−3)=0(x-2)(x-3) = 0

    This gives the roots x=2x=2 and x=3x=3.

    The solutions for the equation x3−6x2+11x−6=0x^3 - 6x^2 + 11x - 6 = 0 are: x=1,x=2,x=3\boxed{x=1, x=2, x=3}

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