Math Problem Statement

Consider the quadratic function:
f ( x )

4 x 2 + 14 x − 6

. Find the following for this parabola.

A) The line of symmetry:

B) The vertex:

C) The vertical intercept is the point

D) Give the coordinates of the two
x intercepts of the parabola as ordered pairs.

Round your values to two decimal places for this part, if the roots are irrational.

Solution

We are given the quadratic function:

f(x)=4x2+14x6f(x) = 4x^2 + 14x - 6

Let's find the requested information step by step.

A) Line of Symmetry

The line of symmetry for a quadratic function f(x)=ax2+bx+cf(x) = ax^2 + bx + c is given by the formula:

x=b2ax = -\frac{b}{2a}

In this case, a=4a = 4 and b=14b = 14. Substituting into the formula:

x=142(4)=148=1.75x = -\frac{14}{2(4)} = -\frac{14}{8} = -1.75

So, the line of symmetry is:

x=1.75x = -1.75


B) Vertex

The vertex of a parabola is found by using the line of symmetry (which gives the x-coordinate), and then plugging that value back into the quadratic function to find the y-coordinate.

We already know x=1.75x = -1.75. Now, substitute this value into the original equation to find the y-coordinate:

f(1.75)=4(1.75)2+14(1.75)6f(-1.75) = 4(-1.75)^2 + 14(-1.75) - 6

f(1.75)=4(3.0625)24.56=12.2524.56=18.25f(-1.75) = 4(3.0625) - 24.5 - 6 = 12.25 - 24.5 - 6 = -18.25

So, the vertex is:

(1.75,18.25)(-1.75, -18.25)


C) Vertical Intercept

The vertical intercept (y-intercept) occurs when x=0x = 0. To find this, simply substitute x=0x = 0 into the quadratic equation:

f(0)=4(0)2+14(0)6=6f(0) = 4(0)^2 + 14(0) - 6 = -6

So, the vertical intercept is:

(0,6)(0, -6)


D) x-Intercepts (Roots)

To find the x-intercepts, we need to solve the equation f(x)=0f(x) = 0, or:

4x2+14x6=04x^2 + 14x - 6 = 0

We can solve this quadratic equation using the quadratic formula:

x=b±b24ac2ax = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}

Where a=4a = 4, b=14b = 14, and c=6c = -6.

First, calculate the discriminant:

Δ=b24ac=1424(4)(6)=196+96=292\Delta = b^2 - 4ac = 14^2 - 4(4)(-6) = 196 + 96 = 292

Now, substitute the values into the quadratic formula:

x=14±2922(4)=14±2928x = \frac{-14 \pm \sqrt{292}}{2(4)} = \frac{-14 \pm \sqrt{292}}{8}

Approximating 29217.09\sqrt{292} \approx 17.09:

x=14±17.098x = \frac{-14 \pm 17.09}{8}

Now, calculate the two possible solutions:

  1. x1=14+17.098=3.0980.39x_1 = \frac{-14 + 17.09}{8} = \frac{3.09}{8} \approx 0.39
  2. x2=1417.098=31.0983.89x_2 = \frac{-14 - 17.09}{8} = \frac{-31.09}{8} \approx -3.89

So, the x-intercepts (roots) are:

(0.39,0)and(3.89,0)(0.39, 0) \quad \text{and} \quad (-3.89, 0)


Summary of Results:

  • A) Line of symmetry: x=1.75x = -1.75
  • B) Vertex: (1.75,18.25)(-1.75, -18.25)
  • C) Vertical intercept: (0,6)(0, -6)
  • D) x-intercepts: (0.39,0)(0.39, 0) and (3.89,0)(-3.89, 0)

Would you like further explanation on any part?


Here are five related questions:

  1. How can we determine if a quadratic function opens upwards or downwards?
  2. What is the discriminant, and how does it affect the number of roots?
  3. How do you find the vertex form of a quadratic function?
  4. Can every quadratic function have real x-intercepts?
  5. How would the function change if the coefficient of x2x^2 was negative?

Tip: The vertex represents the minimum or maximum point of a quadratic function, depending on whether it opens upward or downward.

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Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Functions
Parabolas

Formulas

Line of symmetry: x = -b/2a
Vertex formula: f(x) = ax^2 + bx + c
Quadratic equation: x = (-b ± √(b^2 - 4ac)) / 2a

Theorems

Quadratic Formula
Properties of Parabolas

Suitable Grade Level

Grades 9-11