Chapter 1: Problem 57
Describe how each formula is a transformation of a toolkit function. Then sketch a graph of the transformation. $$ f(x)=4(x+1)^{2}-5 $$
Short Answer
Expert verified
A parabola shifted left 1 unit, stretched vertically by 4, then moved down 5 units.
Step by step solution
01
Identify the Toolkit Function
The given function is \( f(x) = 4(x+1)^2 - 5 \). The basic toolkit function here is \( y = x^2 \), which is a standard quadratic function represented by a parabola that opens upwards with its vertex at the origin \((0,0)\).
02
Horizontal Shift
Next, observe the transformation inside the parentheses: \((x + 1)^2\). This indicates a horizontal shift. The graph will shift 1 unit to the left because of \((x + 1)\).
03
Vertical Stretch
The coefficient 4 in the expression \(4(x+1)^2\) applies a vertical stretch to the graph of the function. The parabola becomes narrower as the graph is stretched vertically by a factor of 4.
04
Vertical Shift
The term \(-5\) at the end of the equation \(4(x+1)^2 - 5\) represents a vertical shift downward by 5 units. This will move the vertex of the parabola down by 5 units.
05
Vertex Form and Graph Sketch
Combining all transformations, the vertex form \( f(x) = a(x-h)^2 + k \) will have the vertex at \((-1, -5)\). The graph is a parabola opening upwards that is narrow, shifted left by 1 unit, and down by 5 units. Sketch this new graph based on the movements described.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Quadratic Function
A quadratic function is a type of polynomial function that is represented in its standard form as \( y = ax^2 + bx + c \). It is called quadratic because its highest degree term is a square (\( x^2 \)).
- The graph of a quadratic function is a curve called a parabola.
- It usually takes the shape of a "U" and can open upwards or downwards.
- This curve is symmetric around the vertical line that passes through its vertex.
Horizontal Shift
The concept of horizontal shifts allows us to move the entire graph of a function left or right on the coordinate plane. In the given function \( f(x) = 4(x+1)^2 - 5 \), the term inside the parentheses \((x + 1)\) produces this horizontal shift.
- To determine the direction of the shift, observe the sign inside the parentheses.
- If the expression is \((x - h)\), the shift is to the right by \(h\) units.
- If the expression is \((x + h)\), the shift is to the left by \(h\) units.
Vertical Stretch
Vertical stretching refers to the expansion or contraction of a graph in the vertical direction. When we observe a coefficient other than 1 multiplying the square term as in \( 4(x+1)^2 \), it results in a vertical stretch. In this particular formula:
- The coefficient 4 means that every point on the parabola is stretched vertically away from the x-axis by a factor of 4.
- Vertical stretches result in the parabola appearing narrower compared to the standard form.
Parabola
A parabola is a symmetrical open plane curve which is the graph of a quadratic function. It is one of the most recognizable shapes in mathematics due to its consistent properties and applications.
- Parabolas can have different orientations; they can open upwards, downwards, leftwards, or rightwards, based on the function.
- The most common form in quadratic functions is an upward or downward opening.