Algebra Tutorials!
   
 
 
Saturday 23rd of September
 
   
Home
Solving Linear Equations
Systems of Linear Equations
Solving Linear Equations Graphically
Algebra Expressions
Evaluating Expressions and Solving Equations
Fraction rules
Factoring Quadratic Trinomials
Multiplying and Dividing Fractions
Dividing Decimals by Whole Numbers
Adding and Subtracting Radicals
Subtracting Fractions
Factoring Polynomials by Grouping
Slopes of Perpendicular Lines
Linear Equations
Roots - Radicals 1
Graph of a Line
Sum of the Roots of a Quadratic
Writing Linear Equations Using Slope and Point
Factoring Trinomials with Leading Coefficient 1
Writing Linear Equations Using Slope and Point
Simplifying Expressions with Negative Exponents
Solving Equations 3
Solving Quadratic Equations
Parent and Family Graphs
Collecting Like Terms
nth Roots
Power of a Quotient Property of Exponents
Adding and Subtracting Fractions
Percents
Solving Linear Systems of Equations by Elimination
The Quadratic Formula
Fractions and Mixed Numbers
Solving Rational Equations
Multiplying Special Binomials
Rounding Numbers
Factoring by Grouping
Polar Form of a Complex Number
Solving Quadratic Equations
Simplifying Complex Fractions
Algebra
Common Logs
Operations on Signed Numbers
Multiplying Fractions in General
Dividing Polynomials
Polynomials
Higher Degrees and Variable Exponents
Solving Quadratic Inequalities with a Sign Graph
Writing a Rational Expression in Lowest Terms
Solving Quadratic Inequalities with a Sign Graph
Solving Linear Equations
The Square of a Binomial
Properties of Negative Exponents
Inverse Functions
fractions
Rotating an Ellipse
Multiplying Numbers
Linear Equations
Solving Equations with One Log Term
Combining Operations
The Ellipse
Straight Lines
Graphing Inequalities in Two Variables
Solving Trigonometric Equations
Adding and Subtracting Fractions
Simple Trinomials as Products of Binomials
Ratios and Proportions
Solving Equations
Multiplying and Dividing Fractions 2
Rational Numbers
Difference of Two Squares
Factoring Polynomials by Grouping
Solving Equations That Contain Rational Expressions
Solving Quadratic Equations
Dividing and Subtracting Rational Expressions
Square Roots and Real Numbers
Order of Operations
Solving Nonlinear Equations by Substitution
The Distance and Midpoint Formulas
Linear Equations
Graphing Using x- and y- Intercepts
Properties of Exponents
Solving Quadratic Equations
Solving One-Step Equations Using Algebra
Relatively Prime Numbers
Solving a Quadratic Inequality with Two Solutions
Quadratics
Operations on Radicals
Factoring a Difference of Two Squares
Straight Lines
Solving Quadratic Equations by Factoring
Graphing Logarithmic Functions
Simplifying Expressions Involving Variables
Adding Integers
Decimals
Factoring Completely General Quadratic Trinomials
Using Patterns to Multiply Two Binomials
Adding and Subtracting Rational Expressions With Unlike Denominators
Rational Exponents
Horizontal and Vertical Lines
   
Try the Free Math Solver or Scroll down to Tutorials!

 

 

 

 

 

 

 

 
 
 
 
 
 
 
 
 

 

 

 
 
 
 
 
 
 
 
 

Please use this form if you would like
to have this math solver on your website,
free of charge.


Solving a Quadratic Inequality with Two Solutions

Once you have found the two solutions of the quadratic equation:

a · x2 + b · x + c = 0,

you can write down the solution to the quadratic inequality. Table 1 below shows the solutions for each of the four basic types of quadratic inequality.

Note that in Table 1, the x-values that are solutions of the quadratic equation are represented by the letters r1 and r2. We have assumed that r1 is the smaller of the two solutions.

Type of quadratic inequality Solution of quadratic inequality
a · x2 + b · x + c > 0 x < r1 and x > r2
a · x2 + b · x + c < 0 r1 < x < r2
a · x2 + b · x + c 0 x r1 and x r2
a · x2 + b · x + c 0 r1 x r2

Table 1: Solutions for quadratic inequalities.

Figure 1 (below) shows why these inequalities match these particular solutions.

Figure 1.

Example

Solve the quadratic inequality: 4 · x2 - 2 × x + 3 19.

Solution

First, we must manipulate the given inequality to put it into one of the four basic forms. To do this we can subtract 19 from both sides and then divide both sides by four. Note that since we are dividing by a positive number, the direction of the inequality will stay the same.

4 · x2 - 2 · x + 3 19. (Subtract 19 from both sides)

4 · x2 - 2 · x -16 0

Now that the inequality is in one of the standard forms, we need to solve the quadratic equation:

4 · x2 - 2 · x -16 = 0

Solving this quadratic equation with the quadratic formula gives:

Consulting Table 1, the solution to the quadratic inequality consists of the two intervals of x-values: x -2.266 and x 1.766.

Copyrights © 2005-2017