CBSE Mathematics Class XI

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Mathematics - CBSE CLASS XI

Mathematics

 

:: Some important information to be understood ::

1. Concept Of Solving Quadratic Equation by factorization

x² −3 x −4 =0
(x +1) (x − 4) = 0
x +1 = 0 or x − 4 = 0
x = −1 or x = 4

To make a product equal to zero, one of
them or both must be equal to zero. We do not know either x-1 is equal to zero or x-4 equal to zero so that is why we use the word 'or' not 'and.'

Example:

 

2. Concept of Square root and any root which is multiple of 2

In lower secondary we have learned that if x² = 4 then x = 2. Actually the right answer for it is not 2 but
± 2 ( ± 2 is +2 and -2). This is because if (2)², the answer is 4 and if (-2)², the answer is also 4. So the
square root of 4 is ± 2 . It is also the same for fourth root, sixth root and so on. But in certain situation,
the answer will be only one.

Example:

Solve the equation 4x²= 64

Solution:

4x²= 64

x²= 16

x= ±4

3. Comparison method

Example :

Solution:

From the information given, we know that the method that we have to use to solve the question is comparison method.

 

CBSE Mathematics Class XI ( By Mr. Ayaz Khan )
Email Id : [email protected]