Class 10 Maths Formulas

CHAPTER 4

 

QUADRATIC EQUATIONS

 

1.Standard form of a Quadratic Equation is
ax² + bx + c = 0, a ≠ 0
2.Examples of Quadratic Equations:

x² − 6x + 4 = 0
2x² − 7x = 0
3.Examples of equations which are not quadratic:

x + 3/x = x²
x² + 2√x − 3 = 0
4.A real number α is a root of the quadratic equation
ax² + bx + c = 0 if

aα² + bα + c = 0
Then x = α is a solution.

5.Zeros of the quadratic polynomial
ax² + bx + c
are the same as the roots of the quadratic equation
ax² + bx + c = 0
6.Factorisation Method:
If ax² + bx + c = 0 can be factorised into two linear factors,
then equate each factor to 0 to find the roots.
7.Formula Method:
The real roots of
ax² + bx + c = 0
are given by:

(−b ± √(b² − 4ac)) / 2a
where b² − 4ac ≥ 0

8.Nature of the roots depends on the discriminant
D = b² − 4ac
9.For the quadratic equation
ax² + bx + c = 0:

(i)
Two distinct real roots if
b² − 4ac > 0

(ii)
Two real and equal roots if
b² − 4ac = 0

(iii)
No real roots if
b² − 4ac < 0