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Đặt \(A=1992\cdot19911991-1991\cdot19921992\)
\(\Rightarrow A=1992\cdot\left(1991\cdot10001\right)-1991\cdot\left(1992\cdot10001\right)\)
\(\Rightarrow A=1992\cdot1991\cdot10001-1991\cdot1992\cdot10001=0\)
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A = 85^2 + 170.15 + 225;
=85^2+2.85.15+15^2
=(85+15)^2
=100^2
=10000
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c/
C = 1/100-1/100-1/99-1/99-1/98-1/98-1/97-..........-1/3-1/2-1/2-1/1
C = 1/100-1/100-1/1
C = 0-1/1
C = -1
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(-1,32- 23/7) - ( 6,68 + 5/8 - 2/7)
=\(\frac{-806}{175}\)- \(\frac{8877}{1400}\)
=\(\frac{-613}{56}\)
(-1/32 - 23/7) - (6,68 + 5/8 - 2/7)
= -1,32 - 23/7 - 6,68 - 5/8 + 2/7
= (-1,32 - 6,68) - (23/7 - 2/7) - 5/8
= -8 - 3 - 5/8
= -11 - 5/8
= -93/8
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\(\left(2x+1\right)^2+\left|y-1,2\right|=0\)(1)
Ta thấy:\(\hept{\begin{cases}\left(2x+1\right)^2\ge0\\\left|y-1,2\right|\ge0\end{cases}}\)
\(\left(2x+1\right)^2+\left|y-1,2\right|\ge0\)(2)
Từ (1) và (2) suy ra \(\hept{\begin{cases}\left(2x+1\right)^2=0\\\left|y-1,2\right|=0\end{cases}}\)\(\Rightarrow\hept{\begin{cases}2x+1=0\\y-1,2=0\end{cases}}\)\(\Rightarrow\hept{\begin{cases}x=-\frac{1}{2}\\y=1,2\end{cases}}\)
\(\Rightarrow x+y=-\frac{1}{2}+1,2=-0,5+1,2=0,7\)
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\(\Leftrightarrow\left(\frac{1}{2}\right)^{x+1}=\frac{-3}{8}+\frac{1}{2}\)(tự quy đồng)
\(\Leftrightarrow\left(\frac{1}{2}\right)^{x+1}=\frac{1}{8}\)
\(\Leftrightarrow\left(\frac{1}{2}\right)^{x+1}=\left(\frac{1}{2}\right)^3\)
\(\Leftrightarrow x+1=3\)
\(\Leftrightarrow x=3-1\)
\(\Leftrightarrow x=2\)
112,56 -4,81 -(-7,44) + (-35,19)
= 112,56 - 4,81 + 7,44 - 35,19
=(112,56+7,44) - (4,81+35,19)
= 120 - 40
=80