May 20, 2024
4x ^ 2 - 5x - 12 = 0

The Quadratic Equation 4x ^ 2 – 5x – 12 = 0 Solved

Mathematics is a world of numbers, patterns, and formulas, where the beauty of solving complex equations often leads to profound satisfaction and practical applications. Among the various mathematical challenges, quadratic equations stand out as both intriguing and essential. They are not just mere numbers and symbols on a page; they represent a fundamental concept that underpins many aspects of science, engineering, and even finance. In this article, we delve into the intricacies of solving a specific quadratic equation: 4x^2 – 5x – 12 = 0. This equation might appear daunting at first, but with the right approach, it unfolds into a logical and solvable puzzle.

Our journey will take us through different methods of finding the roots of this equation. Whether you’re a student grappling with algebra for the first time, a teacher looking for effective ways to explain this concept, or just a curious mind eager to refresh your mathematical skills, this guide is tailored for you. We’ll explore various techniques including factoring, using the quadratic formula, and completing the square. Each method offers a unique perspective and reinforces the versatile nature of mathematics in problem-solving.

As we dissect this equation, we not only aim to find its solutions but also to appreciate the elegance and utility of quadratic equations in real-world scenarios. So, let’s embark on this mathematical adventure and unlock the secrets of 4x^2 – 5x – 12 = 0.

Understanding Quadratic Equations

quadratic equation
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Quadratic equations form the backbone of algebra, representing a significant leap from linear equations. A typical quadratic equation is expressed in the standard form ax^2 + bx + c = 0, where ‘a’, ‘b’, and ‘c’ are constants, and ‘x’ represents the unknown variable. The most distinctive feature of these equations is the x^2 term, indicating that the variable is squared. Quadratic equations are quintessential in understanding parabolic curves, which graph as U-shaped figures on a coordinate plane. These equations are unique in that they always have two solutions, which may be real or complex numbers. The nature of these solutions is largely determined by the discriminant, which is calculated using the formula b^2 – 4ac. Understanding quadratics is not just an academic exercise but a fundamental tool in various scientific and engineering fields, as they model numerous real-world phenomena.

Solving the Specific Equation

To solve− 4x^2 – 5x – 12 = 0, we identify a=4, b=-5, c=-12. Substituting these into the quadratic formula, we start by calculating the discriminant, which informs us about the nature of the roots (whether they are real and distinct, real and identical, or complex). Following this, we compute the two possible values of x, reflecting the two solutions that a quadratic equation typically has. This process involves arithmetic operations including squaring, square root calculation, addition, subtraction, and division​

Method 1: Factoring

Factoring is one of the simplest methods to solve quadratic equations when feasible. To solve 4x^2 – 5x – 12 = 0 by factoring, we first look for two binomials that when multiplied, yield the original equation. The process involves finding two numbers that multiply to the product of the coefficient of x^2 (a) and the constant term (c), and add up to the coefficient of x (b). In this case, we need two numbers that multiply by -48 (4 * -12) and add up to -5. These numbers are -8 and 6, leading us to rewrite the equation as 4x^2 – 8x + 6x – 12 = 0. Grouping the terms, we get (4x^2 – 8x) + (6x – 12) = 0. Factoring out the common terms gives 4x(x – 2) + 6(x – 2) = 0. Further factoring yields (4x + 6)(x – 2) = 0. Thus, the solutions are x = -3/2 and x = 2.

Method 2: Quadratic Formula

The quadratic formula is a powerful tool for solving any quadratic equation and is derived from completing the square of the general quadratic equation ax^2 + bx + c = 0. The formula states that the solutions for x are given by [-b ± √(b² – 4ac)] / 2a. Applying this to our equation 4x^2 – 5x – 12 = 0, we first identify a = 4, b = -5, and c = -12. Plugging these into the quadratic formula gives us the solutions as x = [-(-5) ± √((-5)² – 4 * 4 * -12)] / 2 * 4. Simplifying this, we find x = [5 ± √(25 + 192)] / 8, which further simplifies to x = [5 ± √217] / 8. Thus, the quadratic formula gives two solutions, which in this case are both real and distinct.

Method 3: Completing the Square

Completing the square is a method that involves manipulating the equation into a perfect square trinomial, allowing us to easily find the roots. To apply this method to 4x^2 – 5x – 12 = 0, we first divide all terms by the coefficient of x^2, yielding x^2 – (5/4)x – 3 = 0. We then add and subtract the square of half the coefficient of x, which in this case is (5/8)^2 = 25/64, resulting in x^2 – (5/4)x + 25/64 – 25/64 – 3 = 0. Simplifying, we get (x – 5/8)^2 = 217/64. Taking the square root of both sides yields x – 5/8 = ±√(217/64), and adding 5/8 to both sides gives x = 5/8 ± √(217/64). This results in two solutions for x, demonstrating the versatility of this method.

Real-World Applications

Quadratic equations are more than just theoretical constructs; they have numerous real-world applications. In physics, they model the motion of objects under constant acceleration, like the trajectory of a ball thrown in the air. In finance, they help in calculating profit maximization problems, where revenue and cost functions are quadratic. Quadratic equations are also pivotal in engineering for designing parabolic bridges and satellite dishes, which require precise calculations for optimal performance. In the field of computer graphics, they assist in rendering curves and surfaces

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In summary, solving the quadratic equation 4x^2 – 5x – 12 = 0 through methods like factoring, the quadratic formula, and completing the square, not only deepens our understanding of algebra but also illustrates the practical applications of mathematics in everyday life. This exploration into quadratic equations underscores their significance in various fields, proving that these mathematical concepts are essential tools in both academic and real-world problem-solving.


What are the roots of a quadratic equation?

The roots of a quadratic equation are the values of ‘x’ that make the equation true. They can be found using various methods, such as factoring or the quadratic formula.

Can quadratic equations have complex roots?

Yes, quadratic equations can have complex roots. Complex roots occur when the discriminant (the value inside the square root in the quadratic formula) is negative.

Are there real-world applications of quadratic equations?

Yes, quadratic equations have numerous real-world applications, including in physics (for motion and force problems), engineering (for structural analysis), and economics (for modeling supply and demand).

Where can I learn more about solving quadratic equations?

You can find comprehensive resources and tutorials on solving quadratic equations in mathematics textbooks, online courses, or educational websites.

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