SAT Quadratic Equation

SAT Quadratic Equation

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SAT Quadratic Equation

Part 1: Introduction to Quadratic Equations

Welcome to MKSprep, your trusted SAT preparation center located in Putalisadak, Kathmandu, Nepal. As we continue our journey through SAT math preparation, we’re stepping into the realm of Quadratic Equations, a vital topic for the SAT and many other mathematical applications.

What is a Quadratic Equation?

A quadratic equation is a second-order polynomial equation in a single variable x, with a standard form ax² + bx + c = 0, where x represents a variable, and a, b, and c are constants with ‘a’ not equal to zero.

Characteristics of Quadratic Equations

  1. Parabolic graph: Quadratic equations, when graphed, form a curve called a parabola, which either opens upwards or downwards depending on the coefficient of x².
  2. Roots: A quadratic equation can have two, one, or no real solutions, also known as roots. These roots are the x-values where the parabola crosses the x-axis.

Solving Quadratic Equations

There are several methods to solve quadratic equations, including:

  1. Factoring
  2. Using the quadratic formula
  3. Completing the square
  4. Graphically

Each of these methods has its benefits and is suitable for different quadratic equations. As we move forward in this series, we will delve deeper into each of these methods.

Stay tuned for our next part, where we will be delving into the method of solving quadratic equations by factoring.

Solving Quadratic Equations by Factoring

We’re back with MKSprep’s SAT preparation course, hosted in the vibrant city of Kathmandu, Nepal. Our current topic, Quadratic Equations, brings us to the method of solving quadratic equations by factoring. Factoring is a vital mathematical skill and often the simplest method for solving quadratics when applicable.

Solving Quadratic Equations by Factoring

Factoring transforms a quadratic equation into a product of binomial expressions, allowing us to solve for the variable. When a quadratic equation is set to zero and factored, the Zero Product Property states that at least one of the factors must be zero for the product to be zero. This gives us our solutions or roots.

Steps for Factoring Quadratics

Here’s a basic outline of the steps you should follow:

  1. Set the quadratic equation to equal zero.
  2. Factor the equation (if possible).
  3. Use the Zero Product Property to set each factor equal to zero.
  4. Solve each equation to find the values of x.


Let’s use these steps to solve the quadratic equation x² – 5x + 6 = 0:

  1. The equation is already set to equal zero.
  2. Factor the equation: (x – 2)(x – 3) = 0.
  3. Use the Zero Product Property: x – 2 = 0 and x – 3 = 0.
  4. Solve for x: x = 2, 3.


Try factoring these quadratic equations:

  1. x² – 3x – 10 = 0
  2. x² – 2x – 8 = 0
  3. x² + 5x + 6 = 0

The Quadratic Formula

The Quadratic Formula, x = [-b ± sqrt(b² – 4ac)] / (2a), is derived from the standard form of a quadratic equation, ax² + bx + c = 0. This formula gives us the roots of the equation, taking into account the coefficients of the quadratic (a, b, and c).

The term under the square root, b² – 4ac, is known as the Discriminant. It helps us determine the nature of the roots:

  1. If the discriminant is positive, the equation has two distinct real roots.
  2. The equation has one real root (or a repeated real root) if it’s zero.
  3. If it’s negative, the equation has two complex roots.


Let’s solve the quadratic equation 3x² – 2x – 1 = 0 using the Quadratic Formula:

  1. Identify a, b, and c: a = 3, b = -2, c = -1.
  2. Plug these into the Quadratic Formula: x = [2 ± sqrt((-2)² – 43(-1))] / (2*3) x = [2 ± sqrt(4 + 12)] / 6 x = [2 ± sqrt(16)] / 6 x = [2 ± 4] / 6
  3. Solve for x: x = 1, -1/3.


Solve these quadratic equations using the Quadratic Formula:

  1. x² + 3x – 4 = 0
  2. 2x² – x – 1 = 0
  3. x² – 4x + 4 = 0

Next, we’ll explore another method for solving quadratics: completing the square. Stay tuned!

[Next: Completing the Square]

Part 4: Completing the Square

We’re back with our SAT preparation course at MKSprep, situated in the heart of Kathmandu, Nepal. As we journey further into the world of Quadratic Equations, we’ll now learn another useful technique for solving them: Completing the Square.

What is Completing the Square?

Completing the square is a method that involves rearranging and simplifying a quadratic equation into a perfect square trinomial. This form allows us to identify the roots of the equation quickly.

Steps to Complete the Square

Here’s a basic outline of the process:

  1. Ensure the quadratic equation is in the form ax² + bx + c = 0 and that ‘a’ equals 1. If ‘a’ doesn’t equal 1, divide every term by ‘a’.
  2. Move the constant term (c) to the right side of the equation.
  3. Take half of the coefficient of x, square it, and add it to both sides of the equation.
  4. Simplify and rewrite the left side as a squared binomial and the right side as a single number.
  5. Take the square root of both sides, remembering to consider both positive and negative roots.
  6. Solve for x.


Let’s solve the equation x² – 4x – 5 = 0:

  1. The ‘a’ coefficient already equals 1.
  2. Move ‘c’ to the right side: x² – 4x = 5.
  3. Take half of -4 (which is -2), square it (to get 4), and add to both sides: (x² – 4x + 4) = 5 + 4.
  4. Simplify: (x – 2)² = 9.
  5. Take the square root of both sides: x – 2 = ±3.
  6. Solve for x: x = 2 + 3 or 2 – 3, giving x = 5 or -1.


Try completing the square for these equations:

  1. x² + 6x – 7 = 0
  2. x² – 8x + 12 = 0
  3. 2x² – 4x – 6 = 0

In our next part, we’ll explore solving quadratic equations graphically. Stay tuned!

[Next: Solving Quadratic Equations Graphically]

Part 5: Solving Quadratic Equations Graphically

Continuing our SAT preparation course at MKSprep, Kathmandu, Nepal, we now move to a different approach of solving Quadratic Equations: Graphically. This method can give us a visual perspective of the solutions and the overall behavior of the quadratic function.

Graphing Quadratics

A quadratic equation y = ax² + bx + c can be graphed as a parabola. Depending on the coefficient ‘a’, the parabola opens upwards (if a > 0) or downwards (if a < 0). The vertex is the point at which the parabola reaches its maximum or minimum value (depending on its direction).

Solving Quadratic Equations Graphically

To solve a quadratic equation graphically, we set the equation equal to zero and find the points where the parabola crosses the x-axis. These points are the solutions or roots of the equation.

Note: Graphical solutions may be approximate if they don’t fall exactly on an integer value.


Suppose we have the equation x² – 4x – 5 = 0:

  1. Graph y = x² – 4x – 5. This creates a parabola that opens upwards because the coefficient of x² is positive.
  2. Identify where the parabola intersects the x-axis. These points are the solutions to the equation.


Try graphing these equations and finding the roots:

  1. x² + 6x – 7 = 0
  2. x² – 8x + 12 = 0
  3. x² – 3x – 10 = 0

Real-world Applications of Quadratic Equations

Welcome back to MKSprep’s SAT preparation course in Kathmandu, Nepal. In this installment of our exploration of Quadratic Equations, we’re stepping out of the abstract and into the real world, demonstrating how quadratic equations are used in practical contexts.

Real-world Quadratics

From physics to economics, quadratic equations are used in a wide range of fields. They model various natural phenomena and practical problems. Here are some common applications:

  1. Projectile motion: Quadratics can describe the trajectory of projectiles. The equation h = -16t² + vt + s describes a projectile’s height (h) over time (t), where v is the initial vertical velocity and s is the initial height.
  2. Area calculations: Quadratic equations often come into play when calculating areas, particularly when dimensions are variable.
  3. Profit and loss: In business, quadratic equations can model profit and loss scenarios, optimizing sales and revenue.


Suppose a farmer wants to build a rectangular fence along a river. She has 1200 feet of fencing and doesn’t need to fence along the river. How can she determine the dimensions that will maximize the enclosed area?

  1. Let x be the width of the fence. The length, then, is 1200 – 2x (as fencing has two sides).
  2. The area, A, is given by length times width: A = x(1200 – 2x) = 1200x – 2x².
  3. To maximize the area, we need to find the vertex of this quadratic equation as it opens downwards (a < 0).
  4. The x-coordinate of the vertex, h, is given by -b/(2a), so h = -1200/(2*-2) = 300. So, the width that maximizes the area is 300 feet, and the length is 1200 – 2*300 = 600 feet.


Consider these real-world problems and how quadratics might apply:

  1. A ball is thrown upwards with an initial velocity of 48 feet per second. How long will it take to reach its maximum height?
  2. A company models its profit (P) on the number of units sold (x) with the equation P = -5x² + 300x – 2000. How many units should they sell to maximize profit?

Tips and Strategies for Quadratic Equations on the SAT

You’re back with MKSprep’s SAT preparation course in Kathmandu, Nepal. Having explored various facets of Quadratic Equations, let’s now focus on some tips and strategies specifically designed to help you tackle quadratic questions on the SAT effectively.

Tip 1: Recognize Different Forms

Quadratic equations can be expressed in various forms such as Standard Form (ax² + bx + c = 0), Vertex Form (a(x-h)² + k), and Factored Form (a(x – p)(x – q)). Understanding these different forms can help you identify the quickest route to the solution.

Tip 2: Use the Discriminant

The Discriminant (b² – 4ac) can quickly tell you the nature of the roots of a quadratic equation. If you’re asked about the type of roots without having to find the exact values, consider using the Discriminant.

Tip 3: Apply the Right Method

Depending on the question, you should use factoring, the Quadratic Formula, completing the square, or graphing. Select the method that’s most efficient for the specific problem.

Tip 4: Look for Shortcuts

Sometimes, a question may be solved more quickly by plugging in the answer choices or noticing patterns, especially if the equation is difficult to simplify or factor.

Tip 5: Practice Real-World Problems

Many SAT questions involve applying quadratic equations to real-world scenarios. Be comfortable with interpreting these problems and setting up the correct equations.

Example Strategy in Action

Suppose you’re given the equation x² – 5x + 6 = 0 to solve. Instead of immediately applying the Quadratic Formula, you notice that it can be factored easily:

x² – 5x + 6 = 0

(x – 2)(x – 3) = 0

Setting each factor equal to zero gives the solutions x = 2, 3.

In our final installment on Quadratic Equations, we will provide you with a comprehensive review and some practice questions to test your understanding.

[Next: Comprehensive Review and Practice]

Comprehensive Review and Practice

Welcome to the final part of our SAT preparation course at MKSprep, Kathmandu, Nepal, focused on Quadratic Equations. This section comprehensively reviews what we’ve covered and some practice questions to consolidate your understanding.


Let’s summarize the main points we’ve learned about Quadratic Equations:

  1. Standard form: Quadratics are typically written in the standard form ax² + bx + c = 0.
  2. Factoring: We use this method when we can easily factorize the quadratic into two binomial expressions.
  3. Quadratic formula: When a quadratic equation cannot be easily factored, we can use the quadratic formula x = [-b ± sqrt(b² – 4ac)] / (2a).
  4. Completing the square: This is another useful technique for solving quadratics, particularly helpful when dealing with vertex form.
  5. Graphical solutions: We can solve quadratics by graphing them and finding where the parabola crosses the x-axis.
  6. Real-world applications: Quadratics are used in various fields, including physics, economics, and area calculations.
  7. Strategies for the SAT: Recognizing different forms, using the Discriminant, applying the right method, looking for shortcuts, and practicing real-world problems are all key to tackling quadratic questions effectively on the SAT.


Now, let’s test your understanding with these practice questions:

  1. Solve the quadratic equation: 2x² – 5x – 3 = 0.
  2. A rectangular park is to be designed such that its length is twice its width. If the park’s perimeter is 60 meters, find its dimensions using a quadratic equation.
  3. A ball is thrown upward from the top of a 50-foot cliff with an initial velocity of 20 feet per second. How long will it take for the ball to hit the ground? (Use the equation h = -16t² + vt + s.)

This concludes our SAT prep course on Quadratic Equations. We hope you found it helpful and informative. Remember, the key to mastering these concepts is practice, practice, practice!

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