Math Problem Statement

Use the quadratic equation to solve for x when a = 1, b = -2, and c = -1.

Solution

Let's break down and solve the problem step by step to confirm the solution.

The quadratic formula is given as:

x=b±b24ac2ax = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}

From the given information:

  • a=1a = 1,
  • b=2b = -2,
  • c=1c = -1.

Substituting these into the formula:

x=(2)±(2)24(1)(1)2(1)x = \frac{-(-2) \pm \sqrt{(-2)^2 - 4(1)(-1)}}{2(1)}

Simplify the terms:

  1. (2)=2-(-2) = 2,
  2. (2)2=4(-2)^2 = 4,
  3. 4(1)(1)=4-4(1)(-1) = 4,
  4. So, b24ac=4+4=8b^2 - 4ac = 4 + 4 = 8.

Now substitute: x=2±82x = \frac{2 \pm \sqrt{8}}{2}

Simplify 8\sqrt{8}: 8=42=22.\sqrt{8} = \sqrt{4 \cdot 2} = 2\sqrt{2}.

Thus: x=2±222.x = \frac{2 \pm 2\sqrt{2}}{2}.

Split the terms:

  1. 22=1\frac{2}{2} = 1,
  2. 222=2\frac{2\sqrt{2}}{2} = \sqrt{2}.

So: x=1±2.x = 1 \pm \sqrt{2}.

This provides two solutions: x1=1+2,x2=12.x_1 = 1 + \sqrt{2}, \quad x_2 = 1 - \sqrt{2}.

If you are required to enter exact values, ensure you input these expressions correctly: 1+21 + \sqrt{2} or 121 - \sqrt{2}.

Let me know if you need clarification on any step or further assistance! Here are some related questions for practice:

  1. How do you simplify square roots in quadratic equations?
  2. What does the discriminant b24acb^2 - 4ac indicate about the solutions?
  3. How do you write the final answer if it requires decimal form?
  4. How does changing the sign of bb affect the quadratic formula?
  5. What are the steps for solving a quadratic equation using the formula?

Tip: Always simplify square roots to their simplest radical form before substituting them into the solution.

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Math Problem Analysis

Mathematical Concepts

Quadratic Equations
Simplifying Radicals

Formulas

Quadratic Formula: x = (-b ± √(b² - 4ac)) / 2a

Theorems

Quadratic Formula Theorem

Suitable Grade Level

Grades 9-10