四道 (1)(2X^2-X+1)/(2X+1)>0 (2)1/2X^2-1/3X+1/5≥0 (3)(X-1)/(X-2)>1/2 (4)(X-4)/(X^2+X-2)>0

四道 (1)(2X^2-X+1)/(2X+1)>0 (2)1/2X^2-1/3X+1/5≥0 (3)(X-1)/(X-2)>1/2 (4)(X-4)/(X^2+X-2)>0

(1)配方可得(2x2-x+1)=2(x-1/4)2+7/8>0恒成立所以只需2x+1>0,答案為x>-1/2(2)1/2x2-1/3x+1/5≥0,兩邊同時乘以2,可得x2-2/3x+2/5≥0,配方得(x-1/3)2+2/5-1/9>0恒成立(3)化簡x2-3x+3/2=(x-3/2)2-3/4>0…