若0若0若00y= 4/t+16/(2-t) 得y/4= 1/t+4/(2-t)= 1/t+ 2/(1-t/2)=1/t+1/(1-t/2)+1/(1-t/2)根据(a+b+c)/3 ≥3/(1/a+1/b+1/c)得 1/t+1/(1-t/2)+1/(1-t/2)≥ 9/(t+1-t/2+1-t/2)= 9/2所以y>=(9/2)*4=18当t=1-t/2 得t=2/3 而x=根号2/3
若00y= 4/t+16/(2-t) 得y/4= 1/t+4/(2-t)= 1/t+ 2/(1-t/2)=1/t+1/(1-t/2)+1/(1-t/2)根据(a+b+c)/3 ≥3/(1/a+1/b+1/c)得 1/t+1/(1-t/2)+1/(1-t/2)≥ 9/(t+1-t/2+1-t/2)= 9/2所以y>=(9/2)*4=18当t=1-t/2 得t=2/3 而x=根号2/3