Chapter 1: Problem 45
Solve each equation by factoring or the Quadratic Formula, as appropriate. $$ 4 x^{2}+24 x+40=4 $$
Short Answer
Expert verified
The solution to the equation is \( x = -3 \).
Step by step solution
01
Simplify the Equation
First, let's move all terms to one side of the equation by subtracting 4 from both sides: \[ 4x^2 + 24x + 40 - 4 = 0 \] This simplifies to: \[ 4x^2 + 24x + 36 = 0 \]
02
Factor Out the Greatest Common Factor
Notice that each term in the equation \(4x^2 + 24x + 36 = 0\) is divisible by 4, so we can factor out a 4: \[ 4(x^2 + 6x + 9) = 0 \] By factoring 4, the equation becomes: \( 4(x^2 + 6x + 9) = 0) \).Since 4 cannot be zero, we focus on \( x^2 + 6x + 9 = 0 \).
03
Factor the Quadratic
Now we need to factor the quadratic \( x^2 + 6x + 9 \). This is a perfect square trinomial, and it factors to: \[ (x + 3)^2 = 0 \]
04
Solve for x
Set the factor equal to zero and solve for \( x \): \[ (x + 3)^2 = 0 \] Take the square root of both sides: \[ x + 3 = 0 \] Thus, \( x = -3 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Factoring Quadratics
Factoring quadratics is a powerful technique used to solve quadratic equations. Quadratic equations are polynomials of degree 2, typically in the form of \( ax^2 + bx + c = 0 \), where \( a \), \( b \), and \( c \) are constants. By factoring, we aim to express the quadratic equation as a product of its linear factors, usually in the form \( (mx + n)(px + q) = 0 \). This allows us to apply the zero product property: if the product of two numbers is zero, then at least one of the numbers must be zero.
To factor a quadratic, follow these steps:
To factor a quadratic, follow these steps:
- Identify the quadratic and check if the equation is set to zero.
- Look for a greatest common factor (GCF) among the terms.
- Try factoring by grouping if applicable.
- If not easily factorable, consider using trial and error or the quadratic formula.
Perfect Square Trinomial
A perfect square trinomial is a special form of a quadratic equation. It occurs when a trinomial (a polynomial with three terms) can be written as the square of a binomial. The standard form of a perfect square trinomial is \((ax)^2 + 2abx + b^2\), which factors into \((ax + b)^2\).
Recognizing perfect square trinomials can simplify solving quadratics immensely. Here's how to spot them:
Recognizing perfect square trinomials can simplify solving quadratics immensely. Here's how to spot them:
- The first and last terms are perfect squares.
- The middle term is twice the product of the square roots of the first and last terms.
Greatest Common Factor
The greatest common factor (GCF) plays a vital role in simplifying polynomial expressions before further solving. It is the largest factor that divides all terms of a polynomial evenly.
To find the GCF in quadratics like \(4x^2 + 24x + 36\), you need to:
To find the GCF in quadratics like \(4x^2 + 24x + 36\), you need to:
- Identify common numerical factors among coefficients.
- Identify any common variables and how many times they occur in each term.
- Factor out the GCF from the polynomial, simplifying the equation.
Quadratic Formula
The quadratic formula is a universal method for solving any quadratic equation \( ax^2 + bx + c = 0 \), regardless of whether it is factorable. The formula is:\[x = \frac{{-b \pm \sqrt{{b^2 - 4ac}}}}{2a}\] This formula uses the coefficients of the quadratic and can solve equations where factoring is difficult or impossible.
The applicability of the quadratic formula means:
The applicability of the quadratic formula means:
- There is no need to rely on finding factors manually.
- The discriminant \( b^2 - 4ac \) indicates how many and what type of solutions exist.
- It can always be used as a fallback solution method for any quadratic.