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Methods of Integration

Michael Green

Michael Green

6 min read

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Study Guide Overview

This study guide covers completing the square for integrating expressions involving quadratic polynomials. It explains how to complete the square with and without leading coefficients. The guide also demonstrates using completing the square to apply standard integrals involving arctan and arcsin, provides worked examples and practice questions, and includes a glossary of key terms.

Integration Using Completing the Square

Table of Contents

  1. What is Completing the Square?
  2. Integrating Using Completing the Square
  3. Worked Example
  4. Practice Questions
  5. Glossary
  6. Summary and Key Takeaways

What is Completing the Square?

Introduction

Completing the square is a method used to rewrite quadratic expressions in a way that makes them easier to manipulate, particularly for solving equations and integrating.

Quadratic Expression

A quadratic expression is of the form: ax2+bx+ca{x}^{2} + bx + c

Simple Version of Completing the Square

For a quadratic expression without a leading coefficient: x2+bx+c=(x+b2)2+c(b2)2{x}^{2} + bx + c = \left(x + \frac{b}{2}\right)^{2} + c - \left(\frac{b}{2}\right)^{2}

Example: x26x+2=(x3)2+2(3)2=(x3)27{x}^{2} - 6x + 2 = \left(x - 3\right)^{2} + 2 - \left(-3\right)^{2} = \left(x - 3\right)^{2} - 7

Completing the Square with a Leading Coefficient

When a coefficient is in front of the x2x^{2} term: ax2+bx+c=a(x+b2a)2+ca(b2a)2a{x}^{2} + bx + c = a\left(x + \frac{b}{2a}\right)^{2} + c - a\left(\frac{b}{2a}\right)^{2}

Example: 3x2+12x7=3(x+2)273(2)2=3(x+2)2193{x}^{2} + 12x - 7 = 3\left(x + 2\right)^{2} - 7 - 3\left(2\right)^{2} = 3\left(x + 2\right)^{2} - 19 ...

Question 1 of 7

What is the completed square form of x2+4x+1x^2 + 4x + 1?

(x+2)23(x+2)^2 - 3

(x+4)215(x+4)^2 - 15

(x2)2+5(x-2)^2 + 5

(x4)2+17(x-4)^2 + 17