Question

[Nguyễn Ngọc Lam Trường]

Giúp mình với chiều nay mình nộp rùi T_T

1. Rút gọn các phân thức

a, \(\frac{17xy^3z^4}{34x^3y^2z}\)

b, \(\frac{\text{x^2 - 25}}{5x-x^2}\)

c, \(\frac{y^2-xy}{4xy-4y^2}\)

d. \(\frac{x^2+xz-xy-yz}{x^2+xz+xy+yz}\)

2. Qui đồng mẫu của các phân thức sau:

a, \(\frac{5}{2x-4};\frac{4}{3x-9};\frac{7}{50-25x}\)

b, \(\frac{13}{x+2};\frac{5}{2x-4};\frac{7}{6-3x}\)

c, \(\frac{2}{x+1};\frac{3}{x^2-x+1};\frac{4}{x^3+1}\)

Answer 1

[Ngọc]

a)\(\frac{17xy^3z^4}{34x^3y^2z}\)=\(\frac{17yz^3}{34x^2}\)

Answer 2

[Ngọc]

b)\(\frac{x^2-25}{5x-x^2}\)=\(\frac{\left(x-5\right)\left(x+5\right)}{x\left(5-x\right)}\)=\(\frac{\left(x-5\right)\left(x+5\right)}{-x\left(x-5\right)}\)=\(\frac{-x-5}{x}\)

c)\(\frac{y^2-xy}{4xy-4y^2}\)=\(\frac{y\left(y-x\right)}{4y\left(x-y\right)}=\frac{-y\left(x-y\right)}{4y\left(x-y\right)}=\frac{-1}{4}\)

d)\(\frac{x^2+xz-xy-yz}{x^2+xz+xy+yz}=\frac{x\left(x+z\right)-y\left(x+z\right)}{x\left(x+z\right)+y\left(x+z\right)}=\frac{\left(x+z\right)\left(x-y\right)}{\left(x+z\right)\left(x+y\right)}=\frac{x-y}{x+y}\)