Math Problem Statement

Solve these equations, giving your answers in exact form: (a) x^(2/3) + x^(1/3) - 6 = 0, (b) x^4 + 3x^2 - 10 = 0

Solution

Let's solve the equations given in the image one by one.

(a) x23+x136=0x^{\frac{2}{3}} + x^{\frac{1}{3}} - 6 = 0

To simplify, let y=x13y = x^{\frac{1}{3}}, which means y2=x23y^2 = x^{\frac{2}{3}}. The equation becomes:

y2+y6=0y^2 + y - 6 = 0

This is a quadratic equation. Solving it using the quadratic formula:

y=b±b24ac2ay = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}

Here, a=1a = 1, b=1b = 1, and c=6c = -6:

y=1±124(1)(6)2(1)=1±1+242=1±252y = \frac{-1 \pm \sqrt{1^2 - 4(1)(-6)}}{2(1)} = \frac{-1 \pm \sqrt{1 + 24}}{2} = \frac{-1 \pm \sqrt{25}}{2}

y=1±52y = \frac{-1 \pm 5}{2}

So, the two solutions for yy are:

y=1+52=2ory=152=3y = \frac{-1 + 5}{2} = 2 \quad \text{or} \quad y = \frac{-1 - 5}{2} = -3

Since y=x13y = x^{\frac{1}{3}}, we now cube both sides to find xx:

  • If y=2y = 2, then x=23=8x = 2^3 = 8.
  • If y=3y = -3, then x=(3)3=27x = (-3)^3 = -27.

Thus, the solutions for part (a) are:

x=8orx=27x = 8 \quad \text{or} \quad x = -27


(b) x4+3x210=0x^4 + 3x^2 - 10 = 0

Let z=x2z = x^2, which means z2=x4z^2 = x^4. The equation becomes:

z2+3z10=0z^2 + 3z - 10 = 0

This is also a quadratic equation. Solving it using the quadratic formula:

z=b±b24ac2az = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}

Here, a=1a = 1, b=3b = 3, and c=10c = -10:

z=3±324(1)(10)2(1)=3±9+402=3±492z = \frac{-3 \pm \sqrt{3^2 - 4(1)(-10)}}{2(1)} = \frac{-3 \pm \sqrt{9 + 40}}{2} = \frac{-3 \pm \sqrt{49}}{2}

z=3±72z = \frac{-3 \pm 7}{2}

So, the two solutions for zz are:

z=3+72=2orz=372=5z = \frac{-3 + 7}{2} = 2 \quad \text{or} \quad z = \frac{-3 - 7}{2} = -5

Since z=x2z = x^2, we now solve for xx:

  • If z=2z = 2, then x2=2x^2 = 2, so x=±2x = \pm \sqrt{2}.
  • If z=5z = -5, there are no real solutions because x2=5x^2 = -5 has no real solutions.

Thus, the solutions for part (b) are:

x=±2x = \pm \sqrt{2}


Final Answers:

(a) x=8x = 8 or x=27x = -27
(b) x=±2x = \pm \sqrt{2}

Would you like more details on any part of the solution or have any questions?

Here are five related questions to explore:

  1. How do you factor quadratic equations when solving for variables?
  2. What is the role of substitution in simplifying higher-order equations?
  3. How can the quadratic formula be derived?
  4. What are the conditions for a quadratic equation to have real solutions?
  5. How would complex solutions appear in part (b)?

Tip: When solving higher-order equations, substitution methods can simplify them into more manageable forms like quadratics.

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Math Problem Analysis

Mathematical Concepts

Algebra
Substitution
Quadratic Equations
Higher-order Polynomials

Formulas

Quadratic equation formula: y = (-b ± √(b² - 4ac)) / 2a
Cubic root transformations

Theorems

Quadratic formula
Fundamental theorem of algebra

Suitable Grade Level

Grades 10-12