[(a+b)÷2]平方-[(a-b)÷2]平方.用因式分解的方法解决,有好评

[ ( a + b ) / 2 ]" - [ ( a - b ) / 2 ]"
= [ ( a + b )" / 4 ] - [ ( a - b )" / 4 ]
= ( 1/4 )[ ( a + b )" - ( a - b )" ]
= ( 1/4 )( a + b + a - b )( a + b - a + b )
= ( 1/4 )( 2a )( 2b )
= ab