Question

What is/are the following and how does it help us solve quadratic equations? Consider pulling an example from one of the lessons to remind yourself/show how the technique helps solve a quadratic equation.

Substitution











Factoring









Zero Product Property

Answer 1

Certainly! Let's explore each of these methods for solving quadratic equations, along with an example to illustrate how they work.

### 1. Substitution

**What is it?**
Substitution involves replacing a variable or part of an expression with another variable or expression to simplify the equation, making it easier to solve.

**How does it help?**
In the context of quadratic equations, substitution can help by transforming a complicated equation into a simpler one, or by solving for one variable in terms of another.

**Example:**
Consider the equation \( x^2 + 4x + 4 = 0 \).
We can identify this quadratic as a perfect square, and we can use substitution to make it clearer:

Let \( y = x + 2 \). Thus, we rewrite our equation as:
\[
y^2 = 0
\]
Now we can easily solve for \( y \):
\[
y = 0 \Rightarrow x + 2 = 0 \Rightarrow x = -2
\]

This substitution allowed us to simplify the equation to a form that was easier to handle.

---

### 2. Factoring

**What is it?**
Factoring involves rewriting the quadratic equation in the form of a product of binomials, which can be set to zero.

**How does it help?**
Factoring helps break down the quadratic into simpler components, allowing us to find its roots more easily.

**Example:**
Consider the quadratic equation \( x^2 + 5x + 6 = 0 \).
We can factor this expression:
\[
(x + 2)(x + 3) = 0
\]
Using the Zero Product Property, we set each factor to zero:
\[
x + 2 = 0 \quad \text{or} \quad x + 3 = 0
\]
Solving these, we find:
\[
x = -2 \quad \text{or} \quad x = -3
\]
Factoring turned our equation into a product that we could easily solve for the roots.

---

### 3. Zero Product Property

**What is it?**
The Zero Product Property states that if the product of two expressions equals zero, then at least one of the expressions must equal zero.

**How does it help?**
This property is fundamental after we have factored a quadratic equation, as it provides a direct method for finding the zeros (roots) of the equation.

**Example:**
From the previous example, where we factored \( x^2 + 5x + 6 = 0 \) into \( (x + 2)(x + 3) = 0 \), we applied the Zero Product Property. Each factor gave us the possible solutions:
\[
x + 2 = 0 \quad \Rightarrow \quad x = -2
\]
\[
x + 3 = 0 \quad \Rightarrow \quad x = -3
\]

In summary, the methods of substitution, factoring, and the Zero Product Property are all essential tools for solving quadratic equations. They allow us to simplify, rearrange, and ultimately find the values of \( x \) that satisfy the equation.