Chapter 11: Problem 77
Find the \(x\) -intercepts of the function given by \(f(x)=4 x^{2}+2 x-3\).
Short Answer
Expert verified
The x-intercepts are respectively found when simplified for both positive and negative values using quadratic substitutions.
Step by step solution
01
Identify the Quadratic Function
The given function is a quadratic function of the form .. It has the coefficients: Suggesting we are dealing with quadratic function
02
Set the Equation to Zero
To find the x-intercepts, set the function equal to zero: .
03
Apply the Quadratic Formula
Use the quadratic formula: used which the values and x represents the needed formula to find elementary quadratic equations.
04
Calculate the Discriminant
First, calculate the discriminant: which represents the delta values from the quadratic form to solve given factors
05
Solve for x using the Quadratic Formula
Substitute the values of a, b, and c into the quadratic formula: which divides as needed to find the respective substituted value
06
Simplify
Simplify the expressions under the square root, and solve for both positive and negative values of x: respectively found which would give our final needed value.
07
State the x-intercepts
Hence, the x-intercepts of the function are found using the correctly termed calculations.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
quadratic formula
A quadratic equation is an equation of the form \[ ax^2 + bx + c = 0 \]
where
where
- \(a\) is the coefficient of the squared term,
- \(b\) is the coefficient of the linear term,
- \(c\) is the constant term.
discriminant
The discriminant is a component of the quadratic formula which appears under the square root symbol, \[ b^2 - 4ac \]. The value of the discriminant helps us determine the nature of the roots for the quadratic equation.
- If the discriminant is positive \((b^2 - 4ac > 0)\), the equation has two distinct real roots.
- If the discriminant is zero \((b^2 - 4ac = 0)\), the equation has exactly one real root (also called a repeated root).
- If the discriminant is negative \((b^2 - 4ac < 0)\), the equation has no real roots, but two complex roots.
x-intercepts
The x-intercepts of a function are the points where the graph of the function crosses the x-axis. To find the x-intercepts of a quadratic function, we need to find the values of \(x\) for which the function equals zero. This means solving the equation \[ f(x) = ax^2 + bx + c = 0 \]. Once we find the roots (solutions) of this equation using the quadratic formula or other methods, we get the x-intercepts. Supposing we have found them as \(x_1\) and \(x_2\), the x-intercepts will be the points \((x_1, 0)\) and \((x_2, 0)\).
solving quadratic equations
To solve quadratic equations, one can use various methods aside from the quadratic formula. Some other common methods include:
- **Factoring**: Express the quadratic equation as the product of two binomials. For example, \[ x^2 - 5x + 6 = (x-2)(x-3) = 0 \].
Then, solve for \(x\) by setting each binomial to zero. - **Completing the Square**: Rewriting the equation to make one side a perfect square trinomial. This involves adding and then subtracting the same value to keep the equation balanced.
- **Graphing**: Plotting the quadratic function and identifying the points where it intersects the x-axis.