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Updated: Jul 28, 2023

You're in Class 11 and you want to excel in Mathematics. You've realised that Class 11 is a big leap as compared to Class 10. Quadratic Equations seems a fairly easy topic to you.

But yet, the questions can get tricky. Solving Quadratic Equations and Inequalities is what you'll learn here.

## Solving Quadratic Equations using the formula

You' have learnt how to solve a quadratic equation by factorisation. But what happens, when you can't find the roots directly. This is when the formula comes in handy!

You'll learn the basic steps in finding the roots of a quadratic equation using the formula, I recommend using the formula only when you find it difficult to find the roots of a quadratic equation directly.

## Nature of the roots of a quadratic equation

Once you find the roots of a quadratic equation using the formula, you'll learn about the Discriminant. You can determine the nature of the roots of a quadratic equation using the Discriminant. Note that, if the discriminant is greater than zero, the roots are unequal and irrational or rational, depending on whether the discriminant is a perfect square.

If the Discriminant is equal to zero, the roots are equal. If the discriminant is lesser than zero, the roots are complex or imaginary. You have a number of problems based on this concept.

## Sum and Product of the roots of a quadratic equation

You'll learn how to calculate the sum and product of the roots of a quadratic equation using a simple formula. This formula enables you to find the sum and product of the roots of a quadratic equation without actually calculating the roots. Again, this is a very important formula, with tremendous applications, and also asked in SAT examinations.

In this context, learn cases when the roots are reciprocal of each other, one root is unity, the roots are equal and more. Moving on, you'll learn about the sign of the quadratic equation. Note that in a quadratic equation, if a is positive, we have an upward facing parabola and if a is negative, we have a downward facing parabola.

## Solving Quadratic Equations and Inequalities

Learn how to solve Quadratic Inequalities.This is, in fact the most important part of this chapter. You'll need to learn what is a quadratic inequality and the concept of open and closed interval.

Learn how to solve a quadratic inequality by finding the roots, dividing the number line into intervals and identifying the solution.

This topic has applications in Derivatives and Calculus, so make sure you get it right. An important point to note is that this method works only if the coefficient of the highest power of x is positive. If not, you have to make it positive, by multiplying with -1.

Another important point to remember is that when you have powers of roots, if the power is odd, then the above method of dividing into intervals will not work.

Learn how to solve quadratic inequalities expressed as a quotient. You need to note that if the quotient is negative, cross multiplying will change the inequality. What you need to do is multiply both sides by the square of the denominator.

. In case you need more help, you can contact me for online tutoring on mathews.suman@gmail.com. I can help you learn concepts, problem solving and answering MCQ based questions.

You'll start getting accustomed to the NEP mode of questioning. You can join for a session on Quadratic Equalities and Inequalities or you can just sign up for the entire year. Share this with other students of Class 11 who may benefit from this.