GIÚP E VS Ạ, CẦN NGAY LUÔN CÀNG TỐT, E ĐAG THI NÊN CẦN NHÉ
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Bài 2: Chọn C
Bài 4:
a: \(\widehat{C}=180^0-80^0-50^0=50^0\)
Xét ΔABC có \(\widehat{A}=\widehat{C}< \widehat{B}\)
nên BC=AB<AC
b: Xét ΔABC có AB<BC<AC
nên \(\widehat{C}< \widehat{A}< \widehat{B}\)
2KClO3 -> (t°, MnO2) 2KCl + 3O2
3O2 -> (UV) 2O3
O3 + 2Ag -> Ag2O + O2
4Na + O2 -> (t°) 2Na2O
Na2O + H2O -> 2NaOH
2NaOH + Cl2 -> NaCl + NaClO + H2O
2NaCl -> (đpnc) 2Na + Cl2
H2S + 4Cl2 + 4H2O -> H2SO4 + 8HCl
\(2KClO_3\rightarrow\left(t^o,MnO_2\right)2KCl+3O_2\)
\(3O_2\rightarrow\left(tia.UV\right)2O_3\)
\(2Ag+O_3\rightarrow Ag_2O+O_2\)
\(4Na+O_2\rightarrow2Na_2O\)
\(Na_2O+H_2O\rightarrow2NaOH\)
\(NaOH+HCl\rightarrow NaCl+H_2O\)
\(2NaCl\rightarrow\left(đp\right)2Na+Cl_2\)
\(Cl_2+2H_2O+SO_2\rightarrow H_2SO_4+2HCl\)
g: \(=\dfrac{x^2+2x-x^2-4x-2x+4}{x\left(x-2\right)\left(x+2\right)}=\dfrac{-4x+4}{x\left(x-2\right)\left(x+2\right)}\)
h: \(=\dfrac{2x^2+1-x^2+1-x^2+x-1}{\left(x+1\right)\left(x^2-x+1\right)}\)
\(=\dfrac{x+1}{\left(x+1\right)\left(x^2-x+1\right)}=\dfrac{1}{x^2-x+1}\)
\(e,=\dfrac{1}{x-1}-\dfrac{2x}{\left(x^2+1\right)\left(x-1\right)}=\dfrac{x^2-2x+1}{\left(x^2+1\right)\left(x-1\right)}=\dfrac{\left(x-1\right)^2}{\left(x^2+1\right)\left(x-1\right)}=\dfrac{x-1}{x^2+1}\\ f,=\dfrac{3x-1}{2\left(3x+1\right)}+\dfrac{3x+1}{2\left(3x-1\right)}-\dfrac{6x}{\left(3x-1\right)\left(3x+1\right)}\\ =\dfrac{9x^2-6x+1+9x^2+6x+1-12x}{2\left(3x-1\right)\left(3x+1\right)}=\dfrac{2\left(3x-1\right)^2}{2\left(3x-1\right)\left(3x+1\right)}=\dfrac{3x-1}{3x+1}\)
\(g,=\dfrac{x}{x\left(x-2\right)}-\dfrac{x^2+4x}{x\left(x-2\right)\left(x+2\right)}-\dfrac{2}{x\left(x+2\right)}\\ =\dfrac{x^2+2x-x^2-4x-2x+4}{x\left(x-2\right)\left(x+2\right)}=\dfrac{-4x+4}{x\left(x-2\right)\left(x+2\right)}\\ h,=\dfrac{2x^2+1-x^2+1-x^2+x-1}{\left(x+1\right)\left(x^2-x+1\right)}=\dfrac{x+1}{\left(x+1\right)\left(x^2-x+1\right)}=\dfrac{1}{x^2-x+1}\)