Math Problem Statement

factorise x²+2x+4

Solution

The quadratic expression x2+2x+4x^2 + 2x + 4 cannot be factored into real linear factors because its discriminant is negative. However, it can be factored using complex numbers.

  1. Start by checking the discriminant Δ\Delta: Δ=b24ac\Delta = b^2 - 4ac For the quadratic ax2+bx+c=0ax^2 + bx + c = 0, we have a=1a = 1, b=2b = 2, and c=4c = 4. Substituting these values into the discriminant formula: Δ=(2)24(1)(4)=416=12\Delta = (2)^2 - 4(1)(4) = 4 - 16 = -12 Since Δ=12\Delta = -12, the roots are complex.

  2. The quadratic formula gives the roots: x=b±Δ2a=2±122(1)=2±2i32x = \frac{-b \pm \sqrt{\Delta}}{2a} = \frac{-2 \pm \sqrt{-12}}{2(1)} = \frac{-2 \pm 2i\sqrt{3}}{2} Simplifying: x=1±i3x = -1 \pm i\sqrt{3}

  3. Using these roots, the quadratic can be written as: x2+2x+4=(x(1+i3))(x(1i3))x^2 + 2x + 4 = \left(x - (-1 + i\sqrt{3})\right)\left(x - (-1 - i\sqrt{3})\right) Or more simply: x2+2x+4=(x+1i3)(x+1+i3)x^2 + 2x + 4 = (x + 1 - i\sqrt{3})(x + 1 + i\sqrt{3})

This is the factorization in terms of complex numbers.

Would you like further clarification or a detailed breakdown of this process?

Here are some related questions:

  1. How can we determine whether a quadratic has real or complex roots?
  2. What are the steps to apply the quadratic formula?
  3. How does the discriminant help in identifying the nature of the roots?
  4. Can all quadratic equations be factored using real numbers?
  5. How do we simplify complex expressions like 12\sqrt{-12}?

Tip: The discriminant b24acb^2 - 4ac is a quick way to check whether a quadratic equation has real or complex roots.

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Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Equations
Complex Numbers

Formulas

Quadratic equation formula: ax² + bx + c = 0
Discriminant: Δ = b² - 4ac
Quadratic formula: x = (-b ± √Δ) / 2a

Theorems

Discriminant theorem for determining the nature of the roots
Quadratic formula theorem

Suitable Grade Level

Grades 9-12