who knows the answer they only give answer otherwise no need. question no. 14 and 15.
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14. ( 25x² - 1 ) + ( 1 + 5x )²
= { ( 5x )² - ( 1 )² } + ( 1 + 5x )²
= ( 5x + 1 ) ( 5x - 1 ) + ( 1 + 5x )²
= ( 1 + 5x ) ( 5x - 1 ) + ( 1 + 5x )²
= ( 1 + 5x ) ( 5x - 1 + 1 + 5x )
= ( 1 + 5x ) ( 10 x ).
So, answer is option ( d ) 10x.
15. 249² - 248²
= ( 249 + 248 ) ( 249 - 248 ) { a² - b² = ( a + b ) ( a - b ) }
= ( 497 ) 1
= 497.
= { ( 5x )² - ( 1 )² } + ( 1 + 5x )²
= ( 5x + 1 ) ( 5x - 1 ) + ( 1 + 5x )²
= ( 1 + 5x ) ( 5x - 1 ) + ( 1 + 5x )²
= ( 1 + 5x ) ( 5x - 1 + 1 + 5x )
= ( 1 + 5x ) ( 10 x ).
So, answer is option ( d ) 10x.
15. 249² - 248²
= ( 249 + 248 ) ( 249 - 248 ) { a² - b² = ( a + b ) ( a - b ) }
= ( 497 ) 1
= 497.
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