Chapter 8: Problem 46
Find any \(x\) -intercepts and the \(y\) -intercept. If no \(x\) -intercepts exist, state this. $$g(x)=x^{2}-6 x+9$$
Short Answer
Expert verified
x-intercept: (3,0); y-intercept: (0,9)
Step by step solution
01
- Determine the x-intercepts
To find the x-intercepts, set the function equal to zero and solve for x. g(x) = x^2 - 6x + 90 = x^2 - 6x + 9Factor the quadratic equation: 0 = (x-3)^2Solve for x: (x-3)^2 = 0x - 3 = 0x = 3Thus, the x-intercept is at (3,0).
02
- Determine the y-intercept
To find the y-intercept, set x equal to 0 and solve for y. g(0) = 0^2 - 6(0) + 9g(0) = 9Thus, the y-intercept is at (0,9).
03
- State the intercepts
The x-intercept is at (3, 0) and the y-intercept is at (0, 9).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
x-intercept
To understand x-intercepts in a quadratic function, let's delve into the details step by step. An x-intercept is where the graph of the function crosses the x-axis. This happens when the output of the function is zero. To find the x-intercept of the given quadratic function:
- Set the quadratic function equal to zero. For instance, if the function is given by \(g(x) = x^2 - 6x + 9\), set it as \(0 = x^2 - 6x + 9\).
- Simplify or factorize the equation. In our case, \(x^2 - 6x + 9\) can be factored as \((x-3)^2\).
- Solve for \(x\). Here, we get \((x-3)^2 = 0\). Thus, \(x = 3\).
y-intercept
Now let's talk about the y-intercept of a quadratic function. The y-intercept is where the graph crosses the y-axis. This happens when the input (or \(x\)) is zero. Let's understand this with our example function \(g(x) = x^2 - 6x + 9\):
- To find the y-intercept, set \(x = 0\) in the function.
- Substitute x with 0 into the equation: \(g(0) = 0^2 - 6(0) + 9\).
- Simplify the equation. Here, \(g(0) = 9\).
quadratic function
Quadratic functions are one of the fundamental structures in algebra and can be represented in the form \(ax^2 + bx + c\), where \(a\), \(b\), and \(c\) are constants. These functions graph into a shape called a parabola. Key features of quadratic functions include:
- The highest degree of the variable \(x\) is 2.
- They can open upwards or downwards depending on the sign of \(a\). If \(a > 0\), the parabola opens upwards, and if \(a < 0\), it opens downwards.
- The vertex is the highest or lowest point on the graph depending on the direction in which the parabola opens.
solving equations
Solving equations, especially quadratic ones, is a critical skill in math. For quadratic equations of the form \(ax^2 + bx + c = 0\), there are several methods to find the solutions (or roots), which are the x-intercepts in the context of graphs. Let's highlight some common methods:
- Factoring: Simplify the quadratic expression into products of binomials and solve for the variable. Like in our example where \(x^2 - 6x + 9\) becomes \((x-3)^2=0\).
- Quadratic Formula: Use the formula \(x = \frac{-b \, \pm \, \sqrt{b^2 - 4ac}}{2a}\) to find the roots directly.
- Completing the Square: Rearrange the equation into a perfect square trinomial form and solve for the variable.
- Graphing: Visually identify the points where the quadratic curve intersects the x-axis.