|M+N|<|M+N|<KhArrK⇔M+N<(K)andM+N<(K)andM+N>(-K)M+N>(−K)
So, |-2x+1|<1hArr-2x+1<1and-2x+1>(-1)|−2x+1|<1⇔−2x+1<1and−2x+1>(−1) hArr-2x<1-1and-2x>(-1)-1⇔−2x<1−1and−2x>(−1)−1 hArr-2x<0and-2x>(-2)⇔−2x<0and−2x>(−2)
Dividing both sides by (-2), hArrxcolor(red)(>)0andxcolor(red)(<)1⇔x>0andx<1 (ineqalities change)