Tìm x,y biết:
5x2 + 5y2 +8xy - 2x + 2y + 2 = 0
y2 + 2y + 4x - 2x+1 + 2 = 0
- Mong các cậu giải thích rõ hộ tớ. Tks.
a, \(5x^2+5y^2+8xy-2x+2y+2=0\)
\(\Leftrightarrow\left(4x^2+4y^2+8xy\right)+\left(x^2-2x+1\right)+\left(y^2+2y+1\right)=0\)
\(\Leftrightarrow\left(2x+2y\right)^2+\left(x-1\right)^2+\left(y+1\right)^2=0\)
\(\Leftrightarrow\left\{{}\begin{matrix}\left(2x+2y\right)^2=0\\\left(x-1\right)^2=0\\\left(y+1\right)^2=0\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}2x+2y=0\\x-1=0\\y+1=0\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}2.1-2.1=0\\x=1\\y=-1\end{matrix}\right.\)
Vậy ...
b, \(y^2+2y+4^x-2^{x+1}+2=0\)
\(\Leftrightarrow\left(y^2+2y+1\right)+\left(4^x-2^{x+1}+1\right)=0\)
\(\Leftrightarrow\left(y+1\right)^2+\left(2^x-1\right)^2=0\Leftrightarrow\left\{{}\begin{matrix}\left(y+1\right)^2=0\\\left(2^x-1\right)^2=0\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}y+1=0\\2^x-1=0\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}y=-1\\2^x=1\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}y=-1\\x=0\end{matrix}\right.\)
Cho x+y=a+b
và \(x^2+y^2=a^2+b^2\)
Chứng minh \(x^3+y^3=a^3+b^3\)
thực hiện phép tính: 9^8.2^8 - (18^4-1) (18^4+1)
rút gọn các biểu thức sau:
a, (2x + 3)^2 + (2x - 3)^2 - 2(4x^2 - 9)
b, (x + 2)^3 + (x-2)^3 + x^3 - 3x(x + 2)(x - 2)
áp dụng hằng đẳng thức nhé
Giúp mình nha các tình yêu tối nay mình phải đi hok rồi!!
Cho a+b=1. Tìm min của \(a^3\) + \(b^3\) + ab?
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Phân tích đa thức thành nhân tử :
x4+64
Tính (x-1/2)2
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