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Graphical Analysis In Exercises \(59-64,\) use a graphing utility to graph the quadratic function. Find the \(x\) -intercept(s) of the graph and compare them with the solutions of the corresponding quadratic equation when \(f(x)=0 .\) $$ f(x)=x^{2}-4 x $$

Short Answer

Expert verified
The \(x\)-intercepts are at \(x = 0\) or \(x = 4\).

Step by step solution

01

Plot the Function

Using a graphing utility, the function \(f(x)=x^{2}-4 x\) is plotted. Observe the graph and where it intersects or touches the \(x\)-axis, because these points are known as the x-intercepts.
02

Find the x-intercepts

The solutions to the equation are also the x-intercepts (where \(y = 0\)). To find them algebraically, set the function \(f(x) = 0\) and solve for \(x\). You will get \(0 = x^{2} - 4x\). From this equation, factor out an \(x\) to get \(0 = x(x - 4)\). This implies \(x = 0\) or \(x = 4\). These are the x-intercepts and can be cross verified from the graph.
03

Compare and Conclude

Compare the x-intercepts found through the algebraic solution and those identified on the graph. They should match. Therefore, the solutions of the quadratic equation when \(f(x) = 0\) are \(x = 0\) and \(x = 4\).

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Key Concepts

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

x-intercepts
The concept of x-intercepts is crucial when analyzing quadratic functions. These are the points where the graph of the function intersects the x-axis. For any given function, the value of \( y \) is zero at the x-intercepts since these points lie directly on the x-axis. In the case of the quadratic function \( f(x) = x^2 - 4x \), the process to find the x-intercepts involves setting the equation to zero, \( f(x) = 0 \).To calculate this, we set up the equation \( x^2 - 4x = 0 \) and factor it: \( x(x - 4) = 0 \). This indicates that the x-intercepts are at \( x = 0 \) and \( x = 4 \). Graphically, these points can be seen where the parabola crosses the x-axis. It's interesting to check the accuracy of these solutions by plotting the function on a graph, as they should perfectly coincide.
Quadratic Equation Solutions
Quadratic equations often have two solutions, which correspond to the x-intercepts of their graphs. The quadratic in question, \( f(x) = x^2 - 4x \), can be solved by factoring. We start by setting the equation to zero: \( x^2 - 4x = 0 \). Factoring this yields \( x(x - 4) = 0 \), giving the solutions \( x = 0 \) and \( x = 4 \).These solutions are also where the graph of the quadratic function intersects the x-axis, hence they are the x-intercepts. The method of solving quadratic equations by factoring is efficient and directly gives the roots, or solutions, of the equation. This way, we can also verify these roots graphically to ensure they match the x-intercepts we identify on a graphing utility.
Graphing Utility
A graphing utility is a powerful tool to visualize functions and easily find key characteristics such as x-intercepts. For the quadratic function \( f(x) = x^2 - 4x \), the use of a graphing utility can help us see the parabola's shape and where it intersects the x-axis.By inputting the function into a graphing device or software, the graph line is generated and evident x-intercepts become visible. These visual x-intercepts can reinforce our algebraic solutions, which in this case are \( x = 0 \) and \( x = 4 \). Such utilities are helpful not only for confirming manually calculated intercepts but also to foster a deeper understanding of the behavior of quadratic functions. They allow students to explore the symmetries and vertex of parabolas, making learning interactive and dynamic.

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