Question

17. Factorise : (x^2-3x) (x^2-3x-1)-20​

Answer 1

Answer:

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Step-by-step explanation:

( x² - 3x ) ( x² - 3x - 1 ) - 20

Let a = x² - 3x ---( 1 )

Now , the expression becomes ,

a( a - 1 ) - 20

= a² - a - 20

= a² - 5a + 4a - 20

= a( a - 5 ) + 4( a - 5 )

= ( a - 5 ) ( a + 4 )

= ( x² - 3x - 5 ) ( x² - 3x + 4 )

Answer 2

Step-by-step explanation:

x² - 3x ) ( x² - 3x - 1 ) - 20

Let a = x² - 3x ---( 1 )

Now , the expression becomes ,

a( a - 1 ) - 20

= a² - a - 20

= a² - 5a + 4a - 20

= a( a - 5 ) + 4( a - 5 )

= ( a - 5 ) ( a + 4 )

= ( x² - 3x - 5 ) ( x² - 3x + 4 )