Open In App

Practice Questions on Quadratic Equations

Last Updated : 23 Jul, 2025
Comments
Improve
Suggest changes
Like Article
Like
Report

Quadratic equations are everyday concepts with real-life applications. Understanding them is essential for solving aptitude and reasoning questions.

This article offers a variety of easy-to-understand quadratic equations questions. Whether you’re a student or want to enhance your aptitude and reasoning skills, these questions and explanations will help you improve your problem-solving abilities.

What is a Quadratic Equation?

To define in simple words , quadratic equation is a 2nd-degree equation with syntax as ax2 + bx + c = 0 , where

  • 'x' is an unknown variable
  • a, b, and c's are constants (real numbers)
  • and a is not equal to 0.

To solve this kind of equation, you can use methods such as factoring, completing the square, or quadratic formula (also known as the Shree Dharacharya formula) . Each method helps find the values of x that satisfy the equation.

Important Formulas / Concepts

  • Standard Form of Quadratic Equation : ax2 + bx + c = 0 where 'x' is an unknown variable , 'a, b, and c' are constants (real numbers) and a is not equal to 0.
  • Roots of Quadratic Equation Formula : x = [- b ± √(b2 – 4ac)]/2a and b2 - 4ac = D is called the Determinant of the quadratic equation.
  • Range of quadratic expression : Maximum and Minimum value of y = ax2 + bx + c = 0 occurs at x = - (b/2a) irrespective of a < 0 or a > 0 respectively .
  • Sum of Roots of Quadratic Equation : Sum of the roots α + β is equal to -b/a ( = - Coefficient of x / Coefficient of x2)
  • Product of Roots of Quadratic Equation : Product of roots α . β is equal to c/a​ ( = Constant term / Coefficient of x2 )
  • Difference of Roots of Quadratic Equation : Difference of roots α - β is equal to √D/a .
  • Relation between roots and coefficient : (x - α) (x - β ) = 0 or x2 -(sum of roots) x + product of roots = 0.

Practice Questions on Quadratic Equations : Solved

1. Solve the quadratic equation using factorization : x2 - 4x + 4 = 0.

x2 - 4x + 4 = 0
\Rightarrow x2- 2x - 2x + 4 = 0
\Rightarrow x(x - 2) - 2 (x - 2) = 0
\Rightarrow (x - 2)(x - 2) = 0
\Rightarrow (x - 2)2 = 0
Therefore x = 2

2. Form a quadratic equation with rational coefficients if one of its root is cot218°

Given one of its root is cot218°
Then , cot218° = (1 + cos 36° )/(1 - cos 36°)
\Rightarrow (1 + (√5 + 1)/4)/(1 - (√5 + 1)/4)
\Rightarrow 5 + 2√5
Hence if α = 5 + 2√5 , β = 5 - 2√5
Therefore , α + β = 10 ; α.β = 25 - 20 = 5
So , the required quadratic equation will be x2 - 10x + 5 = 0

3. One root of mx2 - 10x + 3 = 0 is two third of the other root . Find the sum of the roots.

α + 2α/3 = 10/m
\Rightarrow 5α/3 = 10/m
\Rightarrow α = 6/m

and 2α/3 = 3/m
\Rightarrow2 = 9/m
\Rightarrow 2.36/m2 = 9/m
\Rightarrow m = 8

Therefore , Sum = 10/ m = 10/8 = 5/4.

4. Form a quadratic equation with roots 2 and 3.

Sum of roots = 2 + 3 = 5
Product of roots = 2.3 = 6

Therefore , quadratic equation is given by x2 + (sum of roots)x + (product of roots) = 0
So , the required equation is x2 + 5x + 6 = 0.

5. If x = 1 and x = 2 are solutions of the equation x3 + ax2+ bx + c = 0 and a + b = 1, then find the value b.

a + b + c = -1 so, c = -2
and 8 + 4a + 2b + c = 0
\Rightarrow 4a + 2b = -6 \Rightarrow 2a + b = -3
\Rightarrow a = -4 , b = 5

Hence , a = -4, b = 5 and c = -2.

6.Find the roots of the equation x4 + x3 - 19x2 - 49x - 30 = 0 , given that the roots are all rational numbers.

Since all the roots are rational because , they are the divisors of -30.
The divisors of -30 are 1, 2, 3, 4, 5, 6, 10, 15, 30 and -1,-2,-3,-4,-5,-6,-10,-15,-30.
By remainder theorem , we find that -1,-2,-3 and 5 are the roots .
Hence the roots are -1,-2,-3 and +5.

Practice Questions on Quadratic Equations : Unsolved

1. Solve: 9 + 7x = 7x2
2. If one root is twice of the other , find the quadratic equation .
3. Difference of roots is 2 and their sum is 7 , find the quadratic equation .
4. One root of mx2 - 10x + 3 = 0 is two third of the other root . Find the product of the roots.
5. If the product of the roots of the equation mx2 + 6x + 2m - 1 = 0 is -1 then find m .
6. For what value of a , the difference of the roots of the equation (a - 2)x2 - (a - 4)x - 2 = 0 is equal to 3.
7. For what value of a the sum of the roots of the equation x2 + 2(2 - a - a2)x - a2 = 0 is zero .
8. The number of roots of the quadratic equation 8sec2x - 6secx + 1 = 0.
9. If the roots of the equation 6x2 - 7x + k = 0 are rational , then find k.
10. If x is real then find the maximum value of (3x2 + 9x + 17)/(3x2 + 9x + 7).


Article Tags :

Similar Reads