Looking for a guide on how to solve quadratic inequality problems? From Ramanujan to calculus cocreator Gottfried Leibniz, many of the world's best and brightest mathematical minds have belonged to autodidacts. And, thanks to the Internet, it's easier than ever to follow in their footsteps (or just finish your homework or study for that next big test). With this installment from Internet pedagogical superstar Salman Khan's series of free math tutorials, you'll learn how to find the right answers when working with quadratic inequalities in algebra.
 Hot
 Latest

How To: Calculate Faster Than a Calculator

How To: Find the Percent Given Two Numbers

How To: Find a number given Its percent

How To: Learn Calculus in 20 minutes

How To: Remember "greater than" & "less than" symbols

How To: Do long division without a calculator

How To: Find the area of a parallelogram using geometry

How To: Calculate the area of a parallelogram

Use the quadratic equation: finding the mirror point

How To: Find the Height of a Trapezoid.

How To: Find measure of an exterior angle of a regular polygon

How To: Solve problems involving functions in algebra

How To: Solve direct proportions

How To: Use ">" (greater than) and "<" (less than) symbols

How To: Calculate percent composition for chemistry

How To: Divide small numbers by big numbers

How To: Convert fractions to percents in two steps

How To: Find the area of a circle when you know the diameter

How To: Find the area of a triangle when given 2 sides & angle

How To: Find a missing angle outside of a triangle

How To: Calculate Faster Than a Calculator

How To: Find the Percent Given Two Numbers

How To: Find a number given Its percent

How To: Learn Calculus in 20 minutes

How To: Remember "greater than" & "less than" symbols

How To: Do long division without a calculator

How To: Find the area of a parallelogram using geometry

How To: Calculate the area of a parallelogram

Use the quadratic equation: finding the mirror point

How To: Find the Height of a Trapezoid.

How To: Find measure of an exterior angle of a regular polygon

How To: Solve problems involving functions in algebra

How To: Solve direct proportions

How To: Use ">" (greater than) and "<" (less than) symbols

How To: Calculate percent composition for chemistry

How To: Divide small numbers by big numbers

How To: Convert fractions to percents in two steps

How To: Find the area of a circle when you know the diameter

How To: Find the area of a triangle when given 2 sides & angle

How To: Find a missing angle outside of a triangle
5 Comments
Solving inequalities through factoring as explained in the video may be confused and can not be generalized in case of quadratic inequalities that are in standard form ax^2 + bx + c 0 (or
In general, there are 3 common methods to solve quadratic inequalities:
1. By using the numberline
2. By the algebraic method
3. By graphing.
The simplest way is to use the numberline method. First solve the quadratic equation to get the 2 real roots. Represent these 2 roots on the numberline.
Next use the testpoint approach. I advise you to use as testpoint the origin x = 0.
Substitute this value x = 0 into the inequality to see if it is true? or not true?
If it is true, then the origin is located on the true segment (the solution set)
If it is not true, then the origin is outside the solution set.
Finally, express the answer in the form of interval. Example: (2, 7), (1/3, 7/5] , [ 1, 7]
Share Your Thoughts