Question 5: Factorize x 2 − 21 x + 108

 

 

Question 5: Factorize x 2 − 21 x + 108

Factorization exercises   — Factorization examples

Solution :

To see as how to evaluate an expression for factorization,  we write it;

x^2-21x+108

 

Break -21x   into two parts as   -12x   and   -9x    such that ;

(-12x)+(-9x)=-21x

and

(-12x)(-9x)=108x^2

 

 

So,

=x^2-12x-9x+108

Taking out x common from first two terms and -9 common from last two terms , we get;

=x(x-12)-9(x-12)

or

=[x(x-12)-9(x-12)]

Now (x-12) can be taken as common;

i-e;

=(x-12)[x-9]

or

=(x-12)(x-9)

 

 


 

 

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