Quadratic Equations

Table of Content

What is Quadratic Polynomial

P(x) = ax2 +bx+c   where a≠0

It is a polynomial of degree 2

$P(x) =3x^2-11x-2$
$P(x)=x^2 -x -11$
$P(x)=x^2 + x -897$

Graphing quadratics Polynomial

Lets us assume y= p(x) where p(x) is the polynomial of quadratic type Now we can plot the equation y=p(x) on the Cartesian plane by taking various values of x and y obtained by putting the values. The plot or graph obtained can be of any shapes The zero's of the polynomial are the points where the graph meet x axis in the Cartesian plane. If the graph does not meet x axis ,then the polynomial does not have any zero's. Let us take some useful polynomial and shapes obtained on the Cartesian plane Open Upward and downward Parabola
Open Upward parabola intersecting at single point and Open upward Parabola having no zeroes
Open Downward Parabola having no zeroes

what is a quadratic equation

When we equate Quadratic Polynomial with zero, it is called Quadratic equation
$ax^2 +bx+c =0$ where a ≠0

$x^2 -x -20=0$
$x^2 + x -300 = 0$

It is used in many field and it has many application in Mathematics
For example
John has a area of a rectangular plot is 528 m2.The length of the plot (in meters) is one more than twice its breadth. We need to find the length and breadth of the plot
For solution , we can assume breadth is x ,then lenght would be (2x+1)
Now $528=x(2x+1)$
or $2x^2+x -528 =0$
Which is a quadratic equation and the required representation of the problem mathematically
Solution or root of the Quadratic equation
A real number $\alpha$ is called the root or solution of the quadratic equation if
$a \alpha^2 +b \alpha +c=0$

Some other points to remember
  • The root of the quadratic equation is the zeroes of the polynomial p(x).
  • We know from chapter two that a polynomial of degree can have max two zeroes. So a quadratic equation can have maximum two roots
  • A quadratic  equation has no real roots if b2- 4ac < 0
  • A graphing quadratic  equation is same as graphing quadratic polynomial as explained above
Check out Quadratic equation Quiz
Check out Quadratic Formula Calculator
This page is part of Quadratic equations Class 10 Notes.You can explore other topics on the below link

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Practice Question

Question 1 What is $1 - \sqrt {3}$ ?
A) Non terminating repeating
B) Non terminating non repeating
C) Terminating
D) None of the above
Question 2 The volume of the largest right circular cone that can be cut out from a cube of edge 4.2 cm is?
A) 19.4 cm3
B) 12 cm3
C) 78.6 cm3
D) 58.2 cm3
Question 3 The sum of the first three terms of an AP is 33. If the product of the first and the third term exceeds the second term by 29, the AP is ?
A) 2 ,21,11
B) 1,10,19
C) -1 ,8,17
D) 2 ,11,20

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