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Solve by completing the square. $$2 x^{2}-7 x+3=0$$

Short Answer

Expert verified
The solutions are \(x = \frac{7}{4} \pm \frac{\sqrt{43}}{2}\).

Step by step solution

01

Move Constant to Right Side

Start by isolating the constant term on the right side of the equation. Subtract 3 from both sides: \[ 2x^2 - 7x = -3 \]
02

Divide by Leading Coefficient

Since the leading coefficient is 2, divide every term by 2 to make the coefficient of \(x^2\) equal to 1:\[ x^2 - \frac{7}{2}x = -\frac{3}{2} \]
03

Calculate the Square Term

Take the coefficient of \(x\) (\(-\frac{7}{2}\)), divide it by 2, and square it to complete the square:\[ \left( -\frac{7}{2} \right)^2 = \frac{49}{4} \]Add and subtract this value on the left side.
04

Add and Subtract the Square

Add \(\frac{49}{4}\) to both sides of the equation:\[ x^2 - \frac{7}{2}x + \frac{49}{4} = -\frac{3}{2} + \frac{49}{4} \]
05

Simplify and Complete the Square

Write the left side as a perfect square and simplify the right side:\[ \left(x - \frac{7}{4} \right)^2 = \frac{-6}{4} + \frac{49}{4} = \frac{43}{4} \]
06

Solve for \(x\) by Taking the Square Root

Take the square root of both sides:\[ x - \frac{7}{4} = \pm \sqrt{\frac{43}{4}} \]This simplifies to:\[ x - \frac{7}{4} = \pm \frac{\sqrt{43}}{2} \]
07

Solve for \(x\)

Isolate \(x\) by adding \(\frac{7}{4}\) to both sides:\[ x = \frac{7}{4} \pm \frac{\sqrt{43}}{2} \]

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Quadratic Equations
Quadratic equations are a fundamental concept in algebra, typically presented in the form \( ax^2 + bx + c = 0 \). These equations are characterized by their highest exponent of 2. Understanding quadratic equations is crucial for solving many real-world problems and advanced mathematical challenges.
When dealing with quadratic equations, you're often required to find the values of \(x\) that make the equation true—these are known as the roots or solutions of the equation. There are several methods for solving quadratic equations, including factoring, using the quadratic formula, and completing the square.
Each method offers different benefits, and the choice often depends on the specific equation you're working with. For instance, solving by completing the square, as seen in the exercise here, is a technique that transforms a quadratic equation into a perfect square trinomial. This can then be easily solved by taking the square root.
Solving Equations
Solving equations is a process of finding the values of variables that satisfy the equation. In general, equations can be linear, quadratic, or of higher degrees, depending on the highest power of the variable present.
With quadratic equations, solutions are typically found where the equation equals zero. The steps to solving an equation by completing the square involve either isolating terms, dividing by coefficients, or creating a perfect square trinomial.
These manipulations make it easier to then apply operations such as taking the square root. In the provided example, we isolate \(x\) by using operations that maintain equality, like adding, subtracting, multiplying, or dividing both sides by the same value. The ultimate goal is to express the equation in a form where the variable stands alone on one side.
Polynomial Functions
Polynomial functions are mathematical expressions consisting of variables and coefficients. Quadratic equations are a special type of polynomial function with a degree of two. In our problem, the polynomial \(2x^2 - 7x + 3\) is a quadratic polynomial since the highest power is \(x^2\).
Polynomial functions can be identified by their terms, which are combined using addition, subtraction, and non-negative integer exponentiation of variables. Understanding polynomials and their behavior—including their roots, which are solutions where the polynomial equals zero—is essential for algebraic problem-solving.
Polynomials can be manipulated in many ways, such as factoring, expanding, or simplifying, to help uncover useful properties or find solutions to equations.
Algebraic Manipulation
Algebraic manipulation refers to the set of techniques used to rearrange and simplify algebraic expressions and equations. This includes adding, subtracting, multiplying, dividing, or simplifying expressions where necessary.
In the context of completing the square, algebraic manipulation is key. It includes moving terms from one side of the equation to another, reducing coefficients, and creating perfect squares from quadratic expressions. For example, subtracting 3 from both sides, dividing by 2, and then completing the square all involve precision and understanding of algebraic manipulations.
Mastery of these skills allows for transforming complex equations into simpler forms. This step-by-step breakdown is not just about getting the right answer, but also about deeply understanding the processes and the reasons behind each manipulation.

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