Is ~$\frac{1}{a-b}$~ < b - a ?
(1) a < b.
(2) 1 < ~$\left | a-b \right |$~.
Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
EACH statement ALONE is sufficient.
Statements (1) and (2) TOGETHER are NOT sufficient.
(1)可以判断,(2)说明a-b>1,或者a-b<-1;第一种情况可以判断原式必定不成立,第二种情况可以判断原式必成立,但(2)有这两种情况,所以还是不能判断,选A
1解题方向2选1抉择缓慢
2.计算转换缓慢
判断谁大谁小,相除和1比或者相减和0比。相除注意除数是否是负数,相减注意不要彻底调换不等号两边。
左减右:(1/a-b)-b+a
1/(a−b) < (b - a) 不能推出1/(a−b) >(a-b),右边乘了-1,左边也要乘-1,再改变不等号方向。不等号两边调换可以推出改变不等式的结果,--> (b - a) >1/(a−b)