x+2y - √(x^2 - 4xy + 4y^2)^2
Rút gọn: \(\frac{2x^2-4xy}{x^2+4xy+4y^2}:\frac{4y^2-x^2}{x^2-4xy+4y^2}:\frac{5x^2y-10xy^2}{x^3+6x^2y+12xy^2+8y^3}\)
\(=\frac{2x\left(x-2y\right)}{\left(x+2y\right)^2}:\frac{\left(2y-x\right)\left(2y+x\right)}{\left(x-2y\right)^2}:\frac{5xy\left(x-2y\right)}{\left(x+2y\right)^3}\)
Điều kiện: \(x\ne2y;x\ne-2y;x\ne0;y\ne0\)
\(=\frac{2x\left(x-2y\right)}{\left(x+2y\right)^2}:\frac{\left(2y+x\right)}{\left(x-2y\right)}:\frac{5xy\left(x-2y\right)}{\left(x+2y\right)^3}\)
\(=\frac{2x\left(x-2y\right)}{\left(x+2y\right)^2}\times\frac{x-2y}{x+2y}\times\frac{\left(x+2y\right)^3}{5xy\left(x-2y\right)}=\frac{2\left(x-2y\right)}{5y}\)
Rút gọn: \(\frac{2x^2-4xy}{x^2+4xy+4y^2}:\frac{4y^2-x^2}{x^2-4xy+4y^2}:\frac{5x^2y-10xy^2}{x^3+6x^2y+12xy^2+8y^3}\)
\(=\dfrac{2x\left(x-2y\right)}{\left(x+2y\right)^2}\cdot\dfrac{\left(x-2y\right)^2}{-\left(x-2y\right)\left(x+2y\right)}:\dfrac{5x^2y-10xy^2}{x^3+6x^2y+12xy^3+8y^3}\)
\(=\dfrac{-2x\left(x-2y\right)^2}{\left(x+2y\right)^3}\cdot\dfrac{\left(x+2y\right)^3}{5xy\left(x-2y\right)}\)
\(=\dfrac{-2x\cdot\left(x-2y\right)}{5xy}=\dfrac{-2\left(x-2y\right)}{5y}\)
Rút gọn:
\(\frac{2x^2-4xy}{x^2+4xy+4y^2}\): \(\frac{4y^2-x^2}{x^2-4xy+4y^2}\): \(\frac{5x^2y-10xy^2}{x^3+6x^2y+12xy^2+8y^2}\)
X+2y - √(x^2-4xy +4y^2)^2 (x>=2y)
Rút gọn biểu thức
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X+2y - √(x^2-4xy +4y^2)^2 (x>=2y) Rút gọn biểu thức
\(x+2y-\sqrt{x^2-4xy+4y^2}\)(sửa đề)
\(=x+2y-\sqrt{\left(x-2y\right)^2}\)
\(=x+2y-\left|x-2y\right|\)
\(=x+2y-\left(x-2y\right)\left(vì.x\ge2y\right)\)
\(=x+2y-x+2y\)
\(=4y\)
\(x+2y-\sqrt{x^2-4xy+4y^2}^2\)
\(=x+2y-\sqrt{\left(x-2y\right)^2}^2\)
\(=x+2y-\left(x-2y\right)^2\)
\(=x+2y-x^2+4xy-4y^2\)
\(\dfrac{x}{x-2y}+\dfrac{x}{x+2y}+\dfrac{4xy}{4y^2-x^2}\)
cho x+2y=3. tính a=x^3-x^2+2x+6x^2y+12xy^2+4xy-4y+4y^2+8y^3
Rút gọn:
\(x+2y-\sqrt{\left(x^2-4xy+4y^2\right)^2}\) (x\(\ge\)2y)
\(x+2y-\sqrt{\left(x^2-4xy+4y^2\right)^2}=x+2y-\left|x-2y\right|=x+2y-x+2y=4y\)
D=x^2+4y^2-2x+10+4xy-4y tại x+2y=5
\(D=x^2+4y^2-2x+10+4xy-4y\)
\(=\left(x^2+4y^2+4xy\right)-\left(2x+4y\right)+10\)
\(=\left(x+2y\right)^2-2\left(x+2y\right)+10\)
Thay \(x+2y=5;\)có :
\(D=5^2-2.5+10\)
\(=25-10+10\)
\(=25\)
Vậy...
Tính: \(\frac{x^2+3xy+2y^2}{5x^2+4xy-y^2}-\frac{x^2-5xy+4y^2}{-2x^2+4xy-2y^2}\)
\(\frac{x^2+3xy+2y^2}{5x^2+4xy-y^2}-\frac{x^2-5xy+4y^2}{-2x^2+4xy-2y^2}\)
\(=\frac{x+2y}{5x-y}-\left[-\frac{x-4y}{2\left(x-y\right)}\right]\)
\(=\frac{x+2y}{5x-y}+\frac{x-4y}{2\left(x-y\right)}\)
\(=\frac{\left(x+2y\right).2\left(x-y\right)}{\left(5x-y\right).2\left(x-y\right)}+\frac{\left(x-4y\right).\left(5x-y\right)}{2\left(x-y\right).\left(5x-y\right)}\)
\(=\frac{\left(x+2y\right).2\left(x-y\right)+\left(x-4y\right).\left(5x-y\right)}{2\left(x-y\right).\left(5x-y\right)}\)
\(=\frac{7x^2-19xy}{2\left(x-y\right).\left(5x-y\right)}\)