\(A=\dfrac{2x+7}{\sqrt{x}-1}=\dfrac{2x-2+9}{\sqrt{x}-1}=2\left(\sqrt{x}+1\right)+\dfrac{9}{\sqrt{x}-1}=2\left(\sqrt{x}-1\right)+\dfrac{9}{\sqrt{x}-1}+4\left(x>1\right)\)Ap dung BDT Cauhy cho cac so duong , ta co :

\(2\left(\sqrt{x}-1\right)+\dfrac{9}{\sqrt{x}-1}\text{≥}2\sqrt{2\left(\sqrt{x}-1\right).\dfrac{9}{\sqrt{x}-1}}=6\sqrt{2}\)

⇔ \(2\left(\sqrt{x}-1\right)+\dfrac{9}{\sqrt{x}-1}+4\text{≥ }6\sqrt{2}+4\)

⇒ \(A_{MIN}=6\sqrt{2}+4."="\text{⇔}\) \(2\left(\sqrt{x}-1\right)=\dfrac{9}{\sqrt{x}-1}\) ( tu giai ra nhe ) .

 chiều cao =26.25/(3.5*(1/2))=15 cm

S=((29+29*2)*15)/2=652.5 cm²

100 vien bi la dap an chinh xac

12 16 20 là sai, mình đã thi violympic và kết quả đấy sai rồi

Hieu 2 so la : 35 * 2 = 70

Tong 2 so la : 708 * 2 = 1416

So lon la:[1416 + 70] / 2 =743

-12(x-5) + 7(3-x) =5 

( -12x + 60) + ( 21 - 7x) = 5

 -12x + 60 + 21 - 7x = 5

  -19x + 81 = 5

   -19x = 76

        x = -4

\(10234-111-9999=124\)