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Solve each equation. $$\sqrt{4 x+5}-6=2 x-11$$

Short Answer

Expert verified
x = 5

Step by step solution

01

Isolate the square root term

Add 6 to both sides of the equation to isolate the square root term: \(\sqrt{4x + 5} = 2x - 5\).
02

Eliminate the square root

Square both sides of the equation to eliminate the square root: \((\sqrt{4x + 5})^2 = (2x - 5)^2\). This simplifies to \(4x + 5 = 4x^2 - 20x + 25\).
03

Rearrange the equation

Move all terms to one side of the equation to set it to zero: \(4x + 5 - 4x - 5 = 4x^2 - 20x + 25 - 4x - 5\). Simplify to get: \(0 = 4x^2 - 24x + 20\).
04

Simplify the quadratic equation

Divide the entire equation by 4 to simplify it: \(0 = x^2 - 6x + 5\).
05

Solve the quadratic equation

Factor the quadratic equation: \(x^2 - 6x + 5 = (x - 1)(x - 5) = 0\). Set each factor to zero and solve for x: \(x - 1 = 0\) or \(x - 5 = 0\). This gives \(x = 1\) or \(x = 5\).
06

Verify the solutions

Substitute \(x = 1\) into the original equation: \(\sqrt{4(1) + 5} - 6 = 2(1) - 11\). This simplifies to \(\sqrt{9} - 6 = -9\), which is not true, so \(x = 1\) is not a solution.
07

Verify the second solution

Substitute \(x = 5\) into the original equation: \(\sqrt{4(5) + 5} - 6 = 2(5) - 11\). This simplifies to \(\sqrt{25} - 6 = -1\). As \(5 - 6 = -1\), \(x = 5\) satisfies the equation.

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Key Concepts

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

Isolating the Square Root
Isolating the square root is the first crucial step in solving equations involving square roots. The goal is to get the square root by itself on one side of the equation. In our exercise, we started with the equation \(\sqrt{4x + 5} - 6 = 2x - 11\). To isolate the square root, we add 6 to both sides, resulting in \(\sqrt{4x + 5} = 2x - 5\). This simplification makes it easier to eliminate the square root in the following steps.
Always remember: whatever you do to one side of the equation, you must do to the other to maintain balance.
Breaking down complex expressions into simpler forms helps in progressing towards the solution systematically.
Eliminating Square Roots
Once we've isolated the square root term, the next step involves eliminating it by squaring both sides of the equation. Squaring is effective because it removes the square root symbol and turns the expression into a standard polynomial.
In our example, we square both sides of \(\sqrt{4x + 5} = 2x - 5\). This gives us \(\left(\sqrt{4x + 5}\right)^2 = \left(2x - 5\right)^2\), which simplifies to \(4x + 5 = 4x^2 - 20x + 25\).
Eliminating square roots converts the equation into a format we can solve using algebraic techniques, such as factoring.
Factoring Quadratics
Factoring quadratic equations is a vital skill when solving polynomials. After eliminating the square root, we rearrange our equation into standard quadratic form \(ax^2 + bx + c = 0\). In our case, simplifying leads to \(0 = 4x^2 - 24x + 20\). We then divide by 4 to get \(x^2 - 6x + 5 = 0\).
Next, we factor the quadratic equation: \(x^2 - 6x + 5 = (x - 1)(x - 5)\). Setting each factor to zero, we find \(x - 1 = 0\) or \(x - 5 = 0\), which gives the solutions \(x = 1\) and \(x = 5\).
The factorization simplifies finding the roots of the equation and bridges the gap between isolating terms and verifying solutions.
Verification of Solutions
Verification of solutions ensures that the solutions derived from the quadratic equation are correct and satisfy the original problem. We substitute each solution back into the original equation.
For \(x = 1\), substituting into the original problem gives \(\sqrt{4(1) + 5} - 6 = 2(1) - 11\), which simplifies to \(\sqrt{9} - 6 = -9\). Since this is not true, \(x = 1\) is not a valid solution.
For \(x = 5\), substituting into the original problem results in \(\sqrt{4(5) + 5} - 6 = 2(5) - 11\), simplifying to \(\sqrt{25} - 6 = -1\). As \(5 - 6 = -1\) holds true, \(x = 5\) is a valid solution.
Verification is essential to confirm that the solutions meet the initial equation's requirements, avoiding errors and ensuring correctness.

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