thực hiện phép tính (các phép tính về phân thức)
\(\frac{1}{x\left(x+y\right)}+\frac{1}{y\left(x+y\right)}+\frac{1}{x\left(x-y\right)}+\frac{1}{y\left(y-x\right)}\)
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
ĐK: \(x,y\ne0,x\ne\pm y\)
Phép tính trên bằng:
\(\left(\frac{\left(x-y\right)\left(x+y\right)}{xy}-\frac{1}{x+y}.\frac{x^3-y^3}{xy}\right):\frac{x-y}{x}\)
\(=\left(\frac{\left(x-y\right)\left(x+y\right)^2}{xy\left(x+y\right)}-\frac{\left(x-y\right)\left(x^2+xy+y^2\right)}{\left(x+y\right)xy}\right):\frac{x-y}{x}\)
\(=\left(\frac{\left(x-y\right)\left(x^2+2xy+y^2-x^2-xy-y^2\right)}{xy\left(x+y\right)}\right):\frac{x-y}{x}\)
\(=\frac{\left(x-y\right)xy}{xy\left(x+y\right)}.\frac{x}{x-y}=\frac{x}{x+y}\)
\(b.=\frac{1\left(c-a\right)}{\left(a-b\right)\left(b-c\right)\left(c-a\right)}+\frac{1\left(a-b\right)}{\left(a-b\right)\left(b-c\right)\left(c-a\right)}+\frac{1\left(b-c\right)}{\left(a-b\right)\left(b-c\right)\left(c-a\right)}\)
\(=\frac{1c-1a+1a-1b+1b-1c}{\left(a-b\right)\left(b-c\right)\left(c-a\right)}\)
\(=-\frac{2b}{\left(a-b\right)\left(b-c\right)\left(c-a\right)}\)
a/ (\(x^3y^2\)-\(\frac{1}{2}x^3y\) + \(2xy\) - \(2x^2y^3\) + \(xy^2\) - \(4y^2\) =
\(\frac{x^2-yz}{\left(x+y\right)\left(x+z\right)}+\frac{y^2-xz}{\left(x+y\right)\left(y+z\right)}+\frac{z^2-xy}{\left(x+z\right)\left(y+z\right)}\)
\(=\frac{\left(x^2-yz\right).\left(y+z\right)}{\left(x+y\right)\left(x+z\right)\left(y+z\right)}+\frac{\left(y^2-xz\right).\left(x+z\right)}{\left(x+y\right)\left(y+z\right)\left(x+z\right)}+\frac{\left(z^2-xy\right).\left(x+y\right)}{\left(x+z\right)\left(y+z\right)\left(x+y\right)}\)
\(=\frac{x^2y-y^2z+x^2z-yz^2+y^2x-x^2z+zy^2-xz^2+z^2x-x^2y+yz^2-xy^2}{\left(x+y\right)\left(x+z\right)\left(y+z\right)}\)
\(=\frac{0}{\left(x+y\right)\left(x+z\right)\left(y+z\right)}\)
\(=0\)\(\left(\text{Đ}K:x+y,y+z,z+x\ne0\right)\)
Tham khảo nhé~