Cho hình vẽ
A B C H
A)So sánh \(\widehat{BAH}\),\(\widehat{C}\)
B) So sánh \(\widehat{CAH,}\),\(\widehat{B}\)
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Đặt \(A=2^{2009}+2^{2008}+...+2^1+2^0\)
Ta có : \(2A=2^{2010}+2^{2009}+...+2^2+2^1\)
\(\Rightarrow2A-A=2^{2010}-2^0\Rightarrow A=2^{2010}-1\)
Do đó : \(M=2^{2010}-A=2^{2010}-\left[2^{2010}-1\right]=1\)
\(M=2^{2010}-\left(2^{2009}+2^{2008}+...+2^1+2^0\right)\)
\(2^{2010}-M=2^{2009}+2^{2008}+...+2+1\)
\(2\left(2^{2010}-M\right)=2\left(2^{2009}+2^{2008}+...+2+1\right)\)
\(2\left(2^{2010}-M\right)=2^{2010}+2^{2009}+...+2^2+2\)
\(2\left(2^{2010}-M\right)-M=\left(2^{2010}+2^{2009}+...+4+2\right)-\left(2^{2009}+2^{2008}+...+2+1\right)\)
\(2^{2010}-M=2^{2010}+2^{2009}+...+4+2-2^{2009}-2^{2008}-...-2-1\)
\(2^{2010}-M=2^{2010}-1\)
=> M = 1
\(a-b=7\Leftrightarrow b=a-7\)
\(\Rightarrow P=\frac{3a-\left(a-7\right)}{2a-7}+\frac{3\left(a-7\right)-a}{2\left(a-7\right)-7}\)
\(=\frac{3a-a+7}{2a-7}+\frac{3a-21-a}{2a-14-7}\)
\(=\frac{2a+7}{2a-7}+\frac{2a-21}{2a-21}\)
\(=\frac{2a+7}{2a-7}+1=\frac{2a+7+2a-7}{2a-7}=\frac{4a}{2a-7}\)
Ta có : \(12x^2+20x+1=4\left[3x^2+5x-2\right]+9=4\cdot0+9=9\)
Vậy giá trị biểu thức là 9
\(M=2x^4+3x^2y^2+y^4+y^2\) với \(x^2+y^2=1\)
\(=2x^2.x^2+2x^2y^2+x^2y^2+y^2y^2+y^2\)
\(=2x^2\left(x^2+y^2\right)+y^2\left(x^2+y^2\right)+y^2\)
\(=2x^2.1+y^2.1+y^2\)
\(=2x^2+y^2+y^2\)
=\(2\left(x^2+y^2\right)\)
\(=2.1=2\)
\(\Rightarrow M=2\)
a/ Ta có : Góc MNy = Góc MNP - Góc PNy = 140-90 = 50 độ
Góc PNx = Góc MNP - Góc MNx = 140-90 = 50 độ
=> Góc MNy = Góc PNx
b, Ta có : Góc xNy = Góc MNP - Góc MNy - Góc PNx = 140 - 50 - 50 = 40 độ
c, Ta có : Góc MNz = Góc MNy + Góc yNz
Góc PNz = Góc PNx + Góc xNz
mà Góc MNy = Góc PNx ( phần a)
Nz là phân giác của góc xNy => Góc yNz = Góc xNz
=> Góc MNz = Góc PNz
=> Nz là phân giác góc MNP
TL:
\(B=2x^2+y^2-2xy-2x+3\)
\(=\left(x^2-2xy+y^2\right)+(x^2-2x+1)+2\)
\(=\left(x-y\right)^2+\left(x-1\right)^2+2\ge2\forall x;y\)
\(D=\left(x+8\right)^4+\left(x+6\right)^4\ge0\forall x\)
Dấu"=" xảy ra<=> \(\hept{\begin{cases}\left(x+8\right)^4=0\\\left(x+6\right)^4=0\end{cases}}\)
\(\Rightarrow\hept{\begin{cases}x=-8\\x=-6\end{cases}}\)
\(x=\sqrt{x}\Rightarrow x^2-x=0\Rightarrow x\left(x-1\right)\)
\(\orbr{\begin{cases}x=0\\x=1\end{cases}}\)
\(x-\sqrt{x}=0\)
\(\Rightarrow x=\sqrt{x}\)\(\Rightarrow x^2=x\)( bình phương 2 vế )
\(\Rightarrow x^2-x=x\left(x-1\right)=0\)
\(\Rightarrow\orbr{\begin{cases}x=0\\x=1\end{cases}}\)
Vậy \(x=0\)hoặc \(x=1\)
\(\frac{x+5}{2005}+\frac{x+6}{2004}+\frac{x+7}{2003}=-3\)
\(\frac{x+5}{2005}+\frac{x+6}{2004}+\frac{x+7}{2003}+3=0\)
\(\left(\frac{x+5}{2005}+1\right)+\left(\frac{x+6}{2004}+1\right)+\left(\frac{x+7}{2003}+1\right)=0\)
\(\frac{x+5+2005}{2005}+\frac{x+6+2004}{2004}+\frac{x+7+2003}{2003}=0\)
\(\frac{x+2010}{2005}+\frac{x+2010}{2004}+\frac{x+2012}{2003}=0\)
\(\left(x+2010\right)\left(\frac{1}{2005}+\frac{1}{2006}+\frac{1}{2007}\right)=0\)
\(x+2010=0\)
\(x=-2010\)