thang cho dam lua ong

0,013 nhé chắc 100% luôn

\(\text{Câu 1: a) }pthh:R+Cl_2\overset{t^0}{\rightarrow}RCl_2\\ \text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }R\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }R+71\\ \text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }6,5\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }13,6\\ \Rightarrow13,6R=6,5\left(R+71\right)\\ \Rightarrow13,6R=6,5R+461,5\\ \Rightarrow7,1R=77,5\\ \Rightarrow7,1R=461,5\\ \Rightarrow R=65\left(Zn\right)\)

Vậy kim loại cần tìm là Kẽm \(\left(Zn\right)\)

b) \(pthh:Zn+2HCl\rightarrow ZnCl_2+H_2\left(2\right)\)

\(n_{Zn}=\dfrac{m}{M}=\dfrac{6.5}{65}=0,1\left(mol\right)\)

Theo \(pthh\left(2\right):n_{HCl}=2n_{Zn}=2\cdot0,1=0,2\left(mol\right)\)

\(\Rightarrow V_{HCl}=\dfrac{n}{C_M}=\dfrac{0,2}{0,5}=0,4\left(l\right)\)

\(A=\dfrac{x^2+x+1}{x}\\ \\ =\dfrac{x^2}{x}+\dfrac{x}{x}+\dfrac{1}{x}\\ \\ =x+1+\dfrac{1}{x}\)

Áp dụng BDT: Cô-si: \(\dfrac{a}{b}+\dfrac{b}{a}\ge2\)

\(\Rightarrow A=x+1+\dfrac{1}{x}\ge2+1\ge3\)

Dấu "=" xảy ra khi:

\(x=1\)

Vậy \(A_{\left(Min\right)}=3\) khi \(x=1\)

benh chet vi chet roi thi bac si cha phai bo tay

\(B=\dfrac{x^2-2x+2016}{x^2}\\ \\ =\dfrac{x^2}{x^2}-\dfrac{2x}{x^2}+\dfrac{2016}{x^2}\\ \\ =1-\dfrac{2}{x}+\dfrac{2016}{x^2}\\ =\dfrac{2016}{x^2}-\dfrac{2}{x}+\dfrac{1}{2016}+\dfrac{2015}{2016}\\ =\left(\dfrac{2016}{x^2}-\dfrac{2}{x}+\dfrac{1}{2016}\right)+\dfrac{2015}{2016}\\ =2016\left(\dfrac{1}{x^2}-\dfrac{1}{1008x}+\dfrac{1}{2016^2}\right)+\dfrac{2015}{2016}\\ =2016\left(\dfrac{1}{x}-\dfrac{1}{2016}\right)^2+\dfrac{2015}{2016}\)

Do \(2016\left(\dfrac{1}{x}-\dfrac{1}{2016}\right)^2\ge0\forall x\)

\(\Rightarrow B=2016\left(\dfrac{1}{x}-\dfrac{1}{2016}\right)^2+\dfrac{2015}{2016}\ge\dfrac{2015}{2016}\forall x\)

Dấu "=" xảy ra khi:

\(2016\left(\dfrac{1}{x}-\dfrac{1}{2016}\right)^2=0\\ \Leftrightarrow\dfrac{1}{x}-\dfrac{1}{2016}=0\\ \Leftrightarrow\dfrac{1}{x}=\dfrac{1}{2016}\\ \Leftrightarrow x=2016\)

Vậy \(B_{Min}=\dfrac{2015}{2016}\) khi \(x=2016\)

hay ghê ha, doc zong cuoi lien..

hahahaha..

500 cm3

TIC CHO MIK NHA!!!!!!!!!!!!!!