Chapter 6: Problem 68
Solve each equation. See Examples I through 9. (A few exercises are linear equations.) $$ x^{2}+22 x+121=0 $$
Short Answer
Expert verified
The solution to the equation is \( x = -11 \).
Step by step solution
01
Identify the Equation Type
The given equation is a quadratic equation in the standard form, where the general structure is \( ax^2 + bx + c = 0 \). In this case, \( a = 1 \), \( b = 22 \), and \( c = 121 \).
02
Recognize Perfect Square
Notice that the constant term \( c = 121 \) is a perfect square, specifically \( 11^2 \), and the middle term \( 22x \) is twice the product of 11 and x, which indicates the equation might be a perfect square trinomial.
03
Rewrite the Equation
Rewrite the quadratic equation in the form of a perfect square: \((x + 11)^2 = 0\). This is done because \( (x+11)(x+11) = x^2 + 22x + 121 \).
04
Solve for x
To find the value of \( x \), take the square root of both sides of the equation \( (x+11)^2 = 0 \), resulting in \( x + 11 = 0 \).
05
Solve the Linear Equation
Subtract 11 from both sides to solve for \( x \): \( x = -11 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Quadratic Equation
A quadratic equation is a type of polynomial equation in which the highest power of the variable is 2. It's typically written in the form \( ax^2 + bx + c = 0 \), where \( a \), \( b \), and \( c \) are constants, and \( a eq 0 \). In our exercise, this form was \( x^{2} + 22x + 121 = 0 \). Quadratic equations can have different types of solutions, ranging from two real solutions, one real solution, or two complex solutions, depending on the discriminant’s value derived from the quadratic formula.
- Two real and distinct solutions if \( b^2 - 4ac > 0 \).
- One real and repeated solution if \( b^2 - 4ac = 0 \).
- Two complex solutions if \( b^2 - 4ac < 0 \).
Perfect Square Trinomial
A perfect square trinomial is a special type of quadratic equation that can be expressed as the square of a binomial. It takes the general form of \((x + m)^2 = x^2 + 2mx + m^2\) or \((x - m)^2 = x^2 - 2mx + m^2\). In our original problem, we encountered the trinomial \( x^2 + 22x + 121 \), which can be rewritten as the square of a binomial: \((x + 11)^2\).
- The first term \( x^2 \) comes from \( x \times x \).
- The middle term \( 22x \) results from \( 2 \cdot 11 \cdot x \), i.e., twice the product of \( 11 \) and \( x \).
- The last term \( 121 \) is \( 11^2 \), confirming it is a perfect square.
Linear Equations
Once a quadratic equation is rewritten as a perfect square trinomial, it simplifies to a form where we solve it much like a linear equation. In simpler terms, a linear equation is an equation that makes a straight line when it is graphed. Its standard form is \( ax + b = 0 \), with solutions easy to find by isolating \( x \). In our exercise, after transforming the quadratic into \( (x + 11)^2 = 0 \), we derived \( x + 11 = 0 \), a linear equation. Solving this involves basic algebraic steps:
- Subtract \( 11 \) from both sides to isolate \( x \).
- The solution \( x = -11 \) gives the point where the equation is satisfied.