4х^2-4y^2 при х=51;у=49

Question

4х^2-4y^2 при х=51;у=49

Answer 1

4x^2 - 4y^2 = 4( x - y )( x + y ) 
x = 51; y = 49 
4( 51 - 49 )( 51 + 49 ) = 4 * 2 * 100 = 800