SAT Quadratic Equations: A Guide to Advanced Math

Quadratic equations are a major component of the "Passport to Advanced Math" domain on the SAT. This guided path will teach you the essential skills, from algebraic solving methods to the crucial interpretation of their graphs (parabolas).

Section 1: Core Solving Methods

The Foundation: What is a Quadratic?

Start with the core definition of a quadratic equation and use our interactive verifier to understand what the "roots" of an equation represent.

What are Roots?

A Quadratic Equation has the form $$ ax^2 + bx + c = 0 $$

The Roots are the specific values of 'x' that make the equation true (equal to zero). Every quadratic has exactly two roots.

Method 1: Solving by Factoring

Learn the step-by-step process of factoring quadratic expressions to find the roots, a crucial skill for the no-calculator section.

Method 1: Factoring

Goal: Rewrite $$ ax^2 + bx + c = 0 $$ into $$ (x+m)(x+n) = 0 $$.

Shortcut (when a=1): Find two numbers that multiply to 'c' and add to 'b'.

Step 1Identify Coefficients

a=1, b=5, c=6

Step 2Find Factors

Factors of 6 that add to 5: 2 and 3.

Step 3Write Factors

$$ (x+2)(x+3) = 0 $$

Step 4Solve

x = -2, x = -3

Method 2: The Quadratic Formula

Master the universal tool for solving any quadratic equation. Our interactive calculator shows you how to apply the formula step by step.

Method 2: Quadratic Formula

The universal method for any quadratic:

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

The term inside the root, $$ b^2 - 4ac $$, is called the Discriminant.

Step 1Identify Coefficients

a=1, b=5, c=6

Step 2Calculate Discriminant

$$ D = 5^2 - 4(1)(6) = 25 - 24 = 1 $$

Step 3Apply Formula

$$ x = \frac{-5 \pm \sqrt{1}}{2} $$

Step 4Solve

$$ x_1 = -2, x_2 = -3 $$

Section 2: SAT Strategies & Applications

Graphs & Number of Solutions (NEW)

Visually connect the discriminant ($$b^2-4ac$$) to the graph of a parabola and understand how it determines the number of real solutions.

The Discriminant & Graphs

The Discriminant ($$ b^2 - 4ac $$) determines how many times the parabola crosses the x-axis.

$$ x^2 - 4x + 3 = 0 $$

$$ D = 4 $$ (Positive)

Crosses x-axis twice.

Modeling with Quadratic Functions (NEW)

Learn the step-by-step process of translating a real-world SAT word problem (like a projectile's path) into a quadratic function.

Modeling Projectile Motion

Build the equation for a rocket launched from 80ft at 64 ft/s.

Model: $$ h(t) = -16t^2 + v_0t + h_0 $$

Step 1Identify Initial Velocity (v₀)

The problem states velocity is 64 ft/s.

$$ v_0 = 64 $$

Step 2Identify Initial Height (h₀)

The rocket starts from a platform 80 ft high.

$$ h_0 = 80 $$

Step 3Assemble Equation

Substitute values into the model:

$$ h(t) = -16t^2 + 64t + 80 $$
Interactive Practice

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