Question

Expand using suitable identity
(2m -n)²​

Answer 1

Property used in the solutions : —

i - ( a - b )( a - b ) = ( a - b )² = a² + b² - 2ab

ii - ( a + b )( a + b ) = ( a + b )² = a² + b² + 2ab

1. ( x - 7 )( x - 7 )

→ ( x - 7 )²

→ ( x )² + ( 7 )² - 2( x × 7 )

→ x² + 49 - 14x

( ii ) : ( 2x + 1 / 4 ) ( 2x + 1 / 4 )

→ ( 2x + 1 / 4 )²

→ ( 2x )² + ( 1 / 4 )² + 2( 2x × 1 / 4 )

→ 4x² + 1 / 16 + x