Chapter 9: Problem 59
Solve using the Square Root Property. $$u^{2}-14 u+49=72$$
Short Answer
Expert verified
u = 7 \pm 6 \sqrt{2}.
Step by step solution
01
Simplify the Equation
First, simplify the given equation: \[ u^{2} - 14u + 49 = 72 \]Move all terms to one side to set the equation equal to zero.\[ u^{2} - 14u + 49 - 72 = 0 \]Simplify the constants:\[ u^{2} - 14u - 23 = 0 \]
02
Add/Subtract to Isolate the Perfect Square
Now, re-write the quadratic equation to recognize the perfect square form. Notice that \( u^2 - 14u + 49 \) is a perfect square equation where:\[ (u - 7)^2 = 72 \].
03
Apply the Square Root Property
Using the Square Root Property, take the square root of both sides of the equation:\[ u - 7 = \pm \sqrt{72} \]Simplify \( \sqrt{72} \):\[ u - 7 = \pm 6 \sqrt{2} \]
04
Solve for u
Finally, solve for \( u \):\[ u = 7 \pm 6 \sqrt{2} \]
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Square Root Property
The Square Root Property is a useful tool when dealing with quadratic equations, especially those that can be expressed as perfect squares. This property states that if we have an equation of the form \( (x - a)^2 = b \), then the solutions can be found by taking the square root of both sides. Specifically, \( x - a = \pm \sqrt{b} \).
In our exercise, the equation \((u - 7)^2 = 72 \) simplified to \( u - 7 = \pm 6 \sqrt{2} \) upon taking the square root of both sides.
In our exercise, the equation \((u - 7)^2 = 72 \) simplified to \( u - 7 = \pm 6 \sqrt{2} \) upon taking the square root of both sides.
- This provided two potential solutions for \( u \).
- By solving these, we get \( u = 7 + 6 \sqrt{2} \) and \( u = 7 - 6 \sqrt{2} \).
Perfect Square Trinomial
A perfect square trinomial is a quadratic expression of the form \( a^2 + 2ab + b^2 \), which can be factored into \( (a + b)^2 \). In our exercise, the given quadratic equation \( u^{2} - 14u + 49 = 72 \) can be re-written in the perfect square form \((u - 7)^2 = 72 \).
Here,
The identification of these forms can make seemingly complex quadratic equations much easier to manage.
Here,
- The middle term \( -14u \) is \( -2 \times u \times 7 \).
- The last term \( 49 \) is \( 7^2 \).
The identification of these forms can make seemingly complex quadratic equations much easier to manage.
Solving Step-by-Step
Understanding how to solve quadratic equations step-by-step is crucial for mastering the material. The breakdown of the problem into smaller steps helps in grasping the fundamental principles behind each method.
In our exercise:
In our exercise:
- Step 1: Simplifying the given equation \( u^{2} - 14u + 49 = 72 \).
- Step 2: Rewriting the quadratic equation \(u^{2} - 14u - 23 = 0\) to have it all terms on one side.
- Step 3: Recognizing the perfect square form \((u - 7)^2 = 72 \).
- Step 4: Applying the Square Root Property \( u - 7 = \pm \sqrt{72} \).
- Step 5: Simplifying the square root, \( \sqrt{72} = 6 \sqrt{2} \).
- Step 6: Solving for \( u \) to get solutions \(u = 7 \pm 6 \sqrt{2}\).