cho P=\(\dfrac{2\sqrt{x}-1}{\sqrt{x}-1}-\dfrac{2\sqrt{x}+1}{\sqrt{x}+1}\)

a)rút gọn b)tìm giá trị của x để P=\(\dfrac{3}{4}\)

cho P=\(\dfrac{x\sqrt{x}-47}{\left(\sqrt{x}-3\right)\left(\sqrt{x}+1\right)}-\dfrac{4\sqrt{x}+12}{\sqrt{x}+1}+\dfrac{\sqrt{x+2}}{\sqrt{x}-3}\)

a)rút gọn b)tìm GTNN

cho x,y,z >0 và x+y+z=4.CMR

\(\dfrac{1}{xy}+\dfrac{1}{xz}\ge1\)

cho x,y,z>0 và x+y+z=1.CMR

\(\dfrac{3}{xy+yz+xz}+\dfrac{2}{x^2+y^2+z^2}\ge14\)

cho a,b>0.CMR

\(\dfrac{a}{\sqrt{a}}+\dfrac{b}{\sqrt{b}}\ge\sqrt{a}+\sqrt{b}\)

1 the weather.....so far this week

A.is B.has been C.was D.had been

2 since the appearance of karaoke machines, they............

A.had been widely used C.were widely used

B.have been widely used D.widely used

3 she...........five cakes since she.........here

A.already ate/was sitting C.has already eaten/is sitting

B.has already eaten/has been sitting D.already ate/had sat

4.they will have have gone home before you..............to meet them

A.came B.come C.will come D.are coming

5.he said he would visit me,but he...............me yet

A.has not visited B.had not visited C.is not visitting D.does not visit