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CBSE Class 10 Quadratic Equations Important Formulas and concepts for exams

CBSE Class 10 Quadratic Equations Important Formulas and concepts for exams. There are many more useful educational material which the students can download in pdf format and use them for studies. Study material like concept maps, important and sure shot question banks, quick to learn flash cards, flow charts, mind maps, teacher notes, important formulas, past examinations question bank, important concepts taught by teachers. Students can download these useful educational material free and use them to get better marks in examinations.  Also refer to other worksheets for the same chapter and other subjects too. Use them for better understanding of the subjects.

POLYNOMIALS

An algebraic expression of the form p(x) = a + a1x + a2x2 + a3x3+ …………….anxn, where a ≠  0, is called a polynomial in variable x of degree n.

Here, a, a1, a2, a3, ………,an are real numbers and each power of x is a non-negative integer. e.g. 3x2  – 5x + 2 is a polynomial of degree 2.

3√ 2 x + is not a polynomial.

• If p(x) is a polynomial in x, the highest power of x in p(x) is called the degree of the polynomial p(x). For example, 4x + 2 is a polynomial in the variable x of degree 1, 2y2– 3y + 4 is a polynomial in the variable y of degree 2,

 • A polynomial of degree 0 is called a constant polynomial.

  • A polynomial p(x) = ax + b of degree 1 is called a linear polynomial.

  • A polynomial p(x) = ax2 + bx + c of degree 2 is called a quadratic polynomial.

  • A polynomial p(x) = ax3 + bx2 + cx + d of degree 3 is called a cubic polynomial.

  • A polynomial p(x) = ax4+ bx3 + cx2 + dx + e of degree 4 is called a bi-quadratic polynomial.

QUADRATIC EQUATION

A polynomial p(x) = ax2 + bx + c of degree 2 is called a quadratic polynomial, then p(x) = 0 is known as quadratic equation.

e.g. 2x2– 3x + 2 = 0, x2 + 5x + 6 = 0 are quadratic equations.

METHODS TO FIND THE SOLUTION OF QUADRATIC EQUATIONS

Three methods to find the solution of quadratic equation:

1. Factorisation method

2. Method of completing the square

3. Quadratic formula method

FACTORISATION METHOD

Steps to find the solution of given quadratic equation by factorisation

  • Firstly, write the given quadratic equation in standard form ax2 + bx + c = 0.

  • Find two numbers a and b such that sum of a and b is equal to b and product of a and b is equal to ac.

  • Write the middle term bx as αx+βx and factorise it by splitting the middle term and let factors are (x + p) and (x + q) i.e. ax2+ bx + c = 0=›(x + p)(x + q) = 0

 • Now equate reach factor to zero and find the values of x.

 • These values of x are the required roots/solutions of the given quadratic equation.

METHOD OF COMPLETING THE SQUARE

Steps to find the solution of given quadratic equation by Method of completing the square:

  • Firstly, write the given quadratic equation in standard form ax2 + bx + c = 0.

  • Make coefficient of x2 unity by dividing all by a then we get x2+b/ax+c/a=0

  • Shift the constant on RHS and add square of half of the coefficient of x i.e. (b/2a)2 on both sides.

   x2 + b/ax = - c/a x2 +2(b/2a)x + (b/2a)2 = - c/a + (b/2a)2
 
• Write LHS as the perfect square of a binomial expression and simplify RHS.
 
   (x + b/2a)2 = b2-4ac /4a2
 
• Take square root on both sides
 
x + b/2a = ±√b2 -4ac/4a2
 
• Find the value of x by shifting the constant term on RHS i.e.
x = ±√b2-4ac/4a2 -b/2a

QUADRATIC FORMULA METHOD

Steps to find the solution of given quadratic equation by quadratic formula method:
• Firstly, write the given quadratic equation in standard form ax2 + bx + c = 0.
 
• Write the values of a, b and c by comparing the given equation with standard form.
 
• Find discriminant D = b2– 4ac. If value of D is negative, then is no real solution i.e. solution does not exist. If value of D≥ 0, then solution exists follow the next step.
 
• Put the value of a, b and D in quadratic formula x = -b ± D /2a and get the required roots/solutions.

NATURE OF ROOTS
The roots of the quadratic equation ax2 + bx + c = 0 by quadratic formula are given by x -b= ± √b2-4ac/4a =  -b ±√D /2a
 
where D = b2 - 4ac is called discriminant. The nature of roots depends upon the value of
discriminant D. There are three cases –
Case – I
When D > 0 i.e. b2 - 4ac > 0, then the quadratic equation has two distinct roots. i.e.  -b + √D /2a and  -b -√D /2a
 
Case – II
When D = 0, then the quadratic equation has two equal real roots.
i.e. x = -b /2a  and  -b /2a 
 
Case – III
When D < 0 then there is no real roots exist.

Please click the link below to download CBSE Class 10 Quadratic Equations Important Formulas and concepts for exams.

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