x"( x - y ) + ( y - x )
= x"( x - y ) - ( x - y )
= ( x - y )( x" - 1 )
= ( x - y )( x - 1 )( x + 1 )
( x - 3 )( x + 2 ) + 25/4
= x" + 2x - 3x - 6 + 6 + 1/4
= x" - x + 1/4
= x" - ( 2 / 2 )x + ( 1/2 )"
= ( x - 1/2 )"
[ ( x + 1 )/x ] / ( x - 1/x )
= [ ( 1/x )( x + 1 ) ] / [ ( 1/x )( x" - 1 ) ]
= ( x + 1 ) / [ ( x + 1 )( x - 1 ) ]
= 1 / ( x - 1 )
= 1 / [ ( √2 + 1 ) - 1 ]
= 1 / ( √2 )
= √2 / 2
2x - 3 >= 1
2x >= 4
x >= 2
( x - 1 )/2 + 2 >= -x
x - 1 + 4 >= -2x
3x + 3 >= 0
3x >= -3
x >= -1
注意：
分子、分母如果写在同一行,
就应该是分子除以分母,如【 分子 / 分母 】