Chapter 2: Problem 7
Express \(f(x)\) in the form \(a(x-h)^{2}+k\) $$f(x)=2 x^{2}-12 x+22$$
Short Answer
Expert verified
The vertex form is \( f(x) = 2(x-3)^2 + 4 \).
Step by step solution
01
Identify the Quadratic Function
You are given a quadratic function in the form of \(f(x) = 2x^2 - 12x + 22\). We want to express it in the vertex form \(f(x) = a(x - h)^2 + k\).
02
Extract the Coefficient 'a'
In the given equation \(f(x) = 2x^2 - 12x + 22\), the coefficient \(a\) of \(x^2\) is 2. This will remain unchanged in the vertex form.
03
Complete the Square
To complete the square, consider the expression \(2(x^2 - 6x)\). Half the coefficient of \(x\) (which is -6) is -3, and it's square is 9. So, add and subtract 9 inside the bracket:1. Rewrite the expression as \(2(x^2 - 6x + 9 - 9)\).2. Simplify to \(2((x-3)^2 - 9)\).
04
Simplify the Expression
Multiply through by the factor 2: \(2((x-3)^2 - 9) = 2(x-3)^2 - 18\). Thus, the original quadratic becomes \(f(x) = 2(x-3)^2 - 18 + 22\).
05
Simplify and Write in Vertex Form
Combine the constants \(-18 + 22\) to get 4.Hence, \(f(x) = 2(x-3)^2 + 4\).This is the vertex form of the given function.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Completing the Square
Completing the square is a method used to transform a quadratic equation into a perfect square trinomial. This process helps rewrite quadratic functions in a way that reveals the vertex form, which is particularly useful for graphing.
To complete the square for a quadratic equation like \( ax^2 + bx + c \), follow these steps:
To complete the square for a quadratic equation like \( ax^2 + bx + c \), follow these steps:
- Factor out the coefficient of \( x^2 \) if it isn't 1. In our example, it is already 2, so we work with \( 2(x^2 - 6x) \).
- Take half of the \( b \) coefficient (where \( b = -6 \) in our case), square it, and add/subtract it within the bracket. Half of \(-6\) is \(-3\), and squaring \(-3\) gives you \(9\).
- Insert \( +9 \) and \( -9 \) inside your equation to keep the function's value unchanged (\( 2(x^2 - 6x + 9 - 9) \)).
- Rewrite the perfect square trinomial \((x^2 - 6x + 9)\) as \((x - 3)^2\).
Quadratic Function
A quadratic function is any function that can be described by the standard form \( f(x) = ax^2 + bx + c \), where \( a \), \( b \), and \( c \) are constants and \( a eq 0 \). These functions graph as a parabola, which can open upwards or downwards depending on the sign of \( a \).
Key features of quadratic functions include:
Key features of quadratic functions include:
- The vertex, which is either the highest or lowest point on the graph.
- The axis of symmetry, a vertical line that splits the parabola into two mirror-image halves.
- The direction the parabola opens, dictated by the sign of \( a \). If \( a \) is positive, the parabola opens upwards; if negative, it opens downwards.
Vertex Form Transformation
Transforming a quadratic function into vertex form involves rearranging it to \( f(x) = a(x-h)^2 + k \). This form highlights the vertex of the parabola, given by the point \((h, k)\).
The main advantages of the vertex form are:
The main advantages of the vertex form are:
- It makes identifying the vertex straightforward, which helps in graphing the parabola efficiently.
- It provides a clear picture of how the parabola shifts from its basic position \( y = ax^2 \), due to \( h \) (horizontal shift) and \( k \) (vertical shift).
- It gives insights into maximum or minimum values directly depending on whether the parabola opens upward or downward.