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

How To: Find the Percent Given Two Numbers

How To: Identify characteristics of a sample during a survey

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

How To: Increase a number by a percentage in basic arithmetic

How To: Find percent by mass & percent composition

How To: Factor a trinomial with a negative in front

How To: Find a number given Its percent

How To: Calculate percent composition for chemistry

How To: Find a missing coordinate given: coordinate & equation

How To: Find the equation of a circle given: center & tangent

How To: Convert Fahrenheit to Celsius with a formula

How To: Find the area & perimeter of triangles & squares

How To: Figure out the domain & range of a piecewise function

How To: Divide and give an answer as a fraction

How To: Simplify a complex fraction w/ binomial denominators

How To: Solve percent proportions

How To: Do long division without a calculator

How To: Calculate Faster Than a Calculator

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

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

How To: Find the Percent Given Two Numbers

How To: Identify characteristics of a sample during a survey

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

How To: Increase a number by a percentage in basic arithmetic

How To: Find percent by mass & percent composition

How To: Factor a trinomial with a negative in front

How To: Find a number given Its percent

How To: Calculate percent composition for chemistry

How To: Find a missing coordinate given: coordinate & equation

How To: Find the equation of a circle given: center & tangent

How To: Convert Fahrenheit to Celsius with a formula

How To: Find the area & perimeter of triangles & squares

How To: Figure out the domain & range of a piecewise function

How To: Divide and give an answer as a fraction

How To: Simplify a complex fraction w/ binomial denominators

How To: Solve percent proportions

How To: Do long division without a calculator

How To: Calculate Faster Than a Calculator

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