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Ch. 1 - Equations and Inequalities
Lial - College Algebra 13th Edition
Lial13th EditionCollege AlgebraISBN: 9780136881063Not the one you use?Change textbook
Chapter 2, Problem 43

Solve each equation using completing the square. 2x2 + x = 10

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1
Start with the given quadratic equation: \$2x^2 + x = 10$.
Divide every term by 2 to make the coefficient of \(x^2\) equal to 1: \(x^2 + \frac{1}{2}x = 5\).
To complete the square, take half of the coefficient of \(x\), which is \(\frac{1}{2}\), divide it by 2 to get \(\frac{1}{4}\), then square it: \(\left(\frac{1}{4}\right)^2 = \frac{1}{16}\).
Add \(\frac{1}{16}\) to both sides of the equation to keep it balanced: \(x^2 + \frac{1}{2}x + \frac{1}{16} = 5 + \frac{1}{16}\).
Rewrite the left side as a perfect square trinomial: \(\left(x + \frac{1}{4}\right)^2 = 5 + \frac{1}{16}\), then solve for \(x\) by taking the square root of both sides and isolating \(x\).

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Completing the Square

Completing the square is a method used to solve quadratic equations by transforming the equation into a perfect square trinomial. This involves adding and subtracting a specific value to both sides to create a binomial squared, making it easier to solve for the variable.
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Quadratic Equation Standard Form

A quadratic equation is typically written in the form ax² + bx + c = 0. To use completing the square, the equation must first be rearranged into this standard form, isolating the quadratic and linear terms on one side and the constant on the other.
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Isolating the Variable

Before completing the square, it is important to isolate the x-terms by dividing through by the coefficient of x² if it is not 1. This simplifies the process of forming a perfect square trinomial and helps in accurately solving for x.
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