\(=\dfrac{18}{\left(x-3\right)^2\cdot\left(x+3\right)}-\dfrac{3}{\left(x-3\right)^2}-\dfrac{x}{\left(x-3\right)\left(x+3\right)}\)
\(=\dfrac{18-3x-9-x^2+3x}{\left(x-3\right)^2\cdot\left(x+3\right)}\)
\(=\dfrac{-x^2+9}{\left(x-3\right)^2\cdot\left(x+3\right)}=\dfrac{-1}{x-3}\)
Thực hiện các phép tính sau :
a) \(\dfrac{x^3-x^2+x-1}{x^2-4}-\dfrac{x-2}{x^2+3x+2}-\dfrac{3x}{x^2-x-2}-\dfrac{2x+5}{\left(x+1\right)\left(4-x^2\right)}\)
b) \(\dfrac{19^2-30x+9}{2x^3+54}-\dfrac{x^3-3}{2^2+6x}-\dfrac{3x^2}{2x^2-6x+18}\)
a)\(\dfrac{2}{x+2}-\dfrac{1}{x+3}+\dfrac{2x+5}{\left(x+2\right)\left(x+3\right)}\)
b)\(\dfrac{2}{x+1}-\dfrac{1}{x+5}+\dfrac{2x+6}{\left(x+5\right)\left(x+1\right)}\)
c)\(\dfrac{-6}{x^2-9}-\dfrac{1}{x+3}+\dfrac{3}{x-3}\)
d)\(\dfrac{x}{x-2}-\dfrac{x}{x+2}+\dfrac{8}{x^2-4}\)
Theo định nghĩa của phép trừ, khi viết :
\(\dfrac{A}{B}-\dfrac{C}{D}-\dfrac{E}{F}\) có nghĩa là \(\dfrac{A}{B}+\dfrac{-C}{D}+\dfrac{-E}{F}\)
Áp dụng điều này để làm các phép tính sau :
a) \(\dfrac{1}{3x-2}-\dfrac{1}{3x+2}-\dfrac{3x-6}{4-9x^2}\)
b) \(\dfrac{18}{\left(x-3\right)\left(x^2-9\right)}-\dfrac{3}{x^2-6x+9}-\dfrac{x}{x^2-9}\)
Tính:
a) \(\dfrac{9-3x}{x^2+3x+4}-\dfrac{3x-23}{\left(1-x\right)\left(x+4\right)}\)
b) \(\dfrac{4-x}{x^3+2x}-\dfrac{x+5}{x^3-x^2+2x-2}\)
c)\(\dfrac{x^2-3}{x^3+2x^2-x-2}-\dfrac{x}{2-x-x}\)
Thực hiện các phép tính :
a) \(\dfrac{x+1}{x-3}-\dfrac{1-x}{x+3}-\dfrac{2x\left(1-x\right)}{9-x^2}\)
b) \(\dfrac{3x+1}{\left(x-1\right)^2}-\dfrac{1}{x+1}+\dfrac{x+3}{1-x^2}\)
Làm tính trừ phân thức :
a) \(\dfrac{3x-2}{2xy}-\dfrac{7x-4}{2xy}\)
b) \(\dfrac{3x+5}{4x^3y}-\dfrac{5-15x}{4x^3y}\)
c) \(\dfrac{4x+7}{2x+2}-\dfrac{3x+6}{2x+2}\)
d) \(\dfrac{9x+5}{2\left(x-1\right)\left(x+3\right)^2}-\dfrac{5x-7}{2\left(x-1\right)\left(x+3\right)^2}\)
e) \(\dfrac{xy}{x^2-y^2}-\dfrac{x^2}{y^2-x^2}\)
f) \(\dfrac{5x+y^2}{x^2y}-\dfrac{5y-x^2}{xy^2}\)
g)\(\dfrac{x}{5x+5}-\dfrac{x}{10x-10}\)
h) \(\dfrac{x+9}{x^2-9}-\dfrac{3}{x^2+3x}\)
a). Chứng minh: \(\dfrac{1}{x}-\dfrac{1}{x+1}=\dfrac{1}{x\left(x+1\right)}\)
b). Tính nhẩm tổng sau:
\(\dfrac{1}{x\left(x+1\right)}+\dfrac{1}{\left(x+1\right)\left(x+2\right)}+\dfrac{1}{\left(x+2\right)\left(x+3\right)}+\dfrac{1}{\left(x+3\right)\left(x+4\right)}+\dfrac{1}{\left(x+4\right)\left(x+5\right)}+\dfrac{1}{x+5}\)
Đố :
Đố em tính nhanh được tổng sau :
\(\dfrac{1}{x\left(x+1\right)}+\dfrac{1}{\left(x+1\right)\left(x+2\right)}+\dfrac{1}{\left(x+2\right)\left(x+3\right)}+\dfrac{1}{\left(x+3\right)\left(x+4\right)}+\dfrac{1}{\left(x+4\right)\left(x+5\right)}+\dfrac{1}{\left(x+5\right)\left(x+6\right)}\)
a) Chứng minh :
\(\dfrac{1}{x}-\dfrac{1}{x+1}=\dfrac{1}{x\left(x+1\right)}\)
b) Đố :
Đố em tính nhẩm được tổng sau :
\(\dfrac{1}{x\left(x+1\right)}+\dfrac{1}{\left(x+1\right)\left(x+2\right)}+\dfrac{1}{\left(x+2\right)\left(x+3\right)}+\dfrac{1}{\left(x+3\right)\left(x+4\right)}+\dfrac{1}{\left(x+4\right)\left(x+5\right)}+\dfrac{1}{x+5}\)
Bài 1: Thực hiện phép chia:
a) \(\dfrac{5}{x}+\dfrac{x}{x+6}-\dfrac{30}{x^2+6x}\) với x ≠ -6 và x ≠ 0
b) \(\dfrac{3x+1}{\left(x-1\right)^2}-\dfrac{1}{x+1}+\dfrac{x+3}{1-x^2}\) với x ≠ \(\pm\)1
c) \(\dfrac{3x^2+2x+1}{x^3-1}-\dfrac{1-x}{x^2+x+1}-\dfrac{2}{x-1}\) với x ≠ 1
