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Write the quadratic function in standard form and sketch its graph. Identify the vertex, axis of symmetry, and \(x\) -intercept(s). $$f(x)=x^{2}+8 x+13$$

Short Answer

Expert verified
The standard form of the function is \(f(x) = (x+2)^2 + 9\). The vertex is at \((-2, 9)\) and the axis of symmetry is \(x = -2\). The function has no x-intercepts. The graph of the function is a parabola opening upwards, with vertex at \((-2, 9)\), symmetric about the line \(x = -2\).

Step by step solution

01

Rewrite the quadratic function in standard form

First, let's rewrite the quadratic function in standard form by completing the square. The given function \(f(x) = x^2 + 8x + 13\). Split the middle term 8x into 2 parts - 4x and 4x - while maintaining its value. So, you can rewrite as \(f(x) = (x^2 + 4x + 4) + 4x + 9\). Notice that \((x^2 + 4x + 4)\) is a perfect square trinomial. It can be written as \((x+2)^2\). Thus, the function in standard form is \(f(x) = (x+2)^2 + 9\)
02

Identify the vertex and axis of symmetry

For the function in standard form \(f(x) = a(x-h)^2 + k\), the vertex is at \((h, k)\). So in our function \(f(x) = (x+2)^2 + 9\), the vertex is at \((-2, 9)\). The axis of symmetry is the vertical line passing through the vertex, which is \(x = h\). Hence, the axis of symmetry in this case is \(x = -2\)
03

Identify x-intercepts

The x-intercepts are the x-values where \(f(x) = 0\). We need to solve the equation \((x+2)^2 + 9 = 0\). Because squaring any real value gives a result greater than or equal to 0 and adding 9 to it will yield a resultant larger than 0, the function has no x-intercepts.
04

Sketch the graph

Plot the vertex, which is the peak of the parabola at \((-2, 9)\). Since the co-efficient of \(x^2\) is positive, the parabola opens upwards. As the equation has no real x-intercepts, so the the parabola does not cross the x-axis. The parabola symmetrically opens upwards about the line \(x = -2\). For a precise sketch, we can plot additional points, though.

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Most popular questions from this chapter

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