Thu gọn biểu thức A = \frac{\text{3x}+\text{21}}{{\text{x}}^{\text{2}}-\text{9}}+\frac{\text{2}}{\text{x}+\text{3}}-\frac{\text{3}}{\text{x}-\text{3}} ta được?

\frac{-\text{2}}{\text{x}-\text{3}}

\frac{\text{2x}}{\text{(x}-\text{3)(x}+\text{3)}}

\frac{\text{2}}{\text{x}+\text{3}}

\frac{\text{2}}{\text{x}-\text{3}}

Cho x; y; z khác ± 1 và xy + yz + xz = 1. Chọn câu đúng ?

\frac{\text{x}}{\text{1}-{\text{x}}^{\text{2}}}+\frac{\text{y}}{\text{1}-{\text{y}}^{\text{2}}}+\frac{\text{z}}{\text{1}-{\text{z}}^{\text{2}}}=\frac{\text{xyz}}{\text{(1}-{\text{x}}^{\text{2}}\text{)(1}-{\text{y}}^{\text{2}}\text{)(1}-{\text{z}}^{\text{2}}\text{)}}

\frac{\text{x}}{\text{1}-{\text{x}}^{\text{2}}}+\frac{\text{y}}{\text{1}-{\text{y}}^{\text{2}}}+\frac{\text{z}}{\text{1}-{\text{z}}^{\text{2}}}=\frac{\text{3xyz}}{\text{(1}-{\text{x}}^{\text{2}}\text{)(1}-{\text{y}}^{\text{2}}\text{)(1}-{\text{z}}^{\text{2}}\text{)}}

\frac{\text{x}}{\text{1}-{\text{x}}^{\text{2}}}+\frac{\text{y}}{\text{1}-{\text{y}}^{\text{2}}}+\frac{\text{z}}{\text{1}-{\text{z}}^{\text{2}}}=\frac{\text{4xyz}}{\text{(1}-{\text{x}}^{\text{2}}\text{)(1}-{\text{y}}^{\text{2}}\text{)(1}-{\text{z}}^{\text{2}}\text{)}}

\frac{\text{x}}{\text{1}-{\text{x}}^{\text{2}}}+\frac{\text{y}}{\text{1}-{\text{y}}^{\text{2}}}+\frac{\text{z}}{\text{1}-{\text{z}}^{\text{2}}}=\frac{\text{xyz(x}+\text{y}+\text{z)}}{\text{(1}-{\text{x}}^{\text{2}}\text{)(1}-{\text{y}}^{\text{2}}\text{)(1}-{\text{z}}^{\text{2}}\text{)}}

Làm tính trừ: \frac{12x}{x-9}-\frac{x-10}{81-{x}^{2}} .

\frac{12{x}^{2}+10x-9}{(x+3)(x-3)}

\frac{12{x}^{2}+109x-9}{(x+3)(x-3)}

\frac{12{x}^{2}+109x-10}{(x+9)(x-9)}

\frac{12{x}^{2}-109x+10}{(x+9)(x-9)}

Chọn người dạy

Khám phá thêm

Câu

trên 16

Bài tập Phép trừ các phân thức đại số (có lời giải chi tiết)

Trắc nghiệm toán lớp 8

Ngày đăng: 21-10-2025

Thời gian làm: 00:26:00

Chia sẻ

Biên soạn tệp:

Đoàn Kim Nguyên

Tổng câu hỏi:

Ngày tạo:

21-10-2025

Tổng điểm:

10 Điểm

Câu hỏi

Số điểm

Lời giải

Câu 1

Rút gọn biểu thức \(\frac{2x-7 }{10x -4} -\frac{3x+5}{4-10x}\) được kết quả ?
- A.
  \(\frac{1}{2}\)
- B.
  \(-\frac{1}{2}\)
- C.
  \(\frac{1}{2x}\)
- D.
  \(\frac{x}{2}\)
Câu 2

Thu gọn biểu thức A = \(\frac{\text{3x}+\text{21}}{{\text{x}}^{\text{2}}-\text{9}}+\frac{\text{2}}{\text{x}+\text{3}}-\frac{\text{3}}{\text{x}-\text{3}}\) ta được?
- A.
  \(\frac{-\text{2}}{\text{x}-\text{3}}\)
- B.
  \(\frac{\text{2x}}{\text{(x}-\text{3)(x}+\text{3)}}\)
- C.
  \(\frac{\text{2}}{\text{x}+\text{3}}\)
- D.
  \(\frac{\text{2}}{\text{x}-\text{3}}\)
Câu 3

Cho x; y; z khác ± 1 và xy + yz + xz = 1. Chọn câu đúng?
- A.
  \(\frac{\text{x}}{\text{1}-{\text{x}}^{\text{2}}}+\frac{\text{y}}{\text{1}-{\text{y}}^{\text{2}}}+\frac{\text{z}}{\text{1}-{\text{z}}^{\text{2}}}=\frac{\text{xyz}}{\text{(1}-{\text{x}}^{\text{2}}\text{)(1}-{\text{y}}^{\text{2}}\text{)(1}-{\text{z}}^{\text{2}}\text{)}}\)
- B.
  \(\frac{\text{x}}{\text{1}-{\text{x}}^{\text{2}}}+\frac{\text{y}}{\text{1}-{\text{y}}^{\text{2}}}+\frac{\text{z}}{\text{1}-{\text{z}}^{\text{2}}}=\frac{\text{3xyz}}{\text{(1}-{\text{x}}^{\text{2}}\text{)(1}-{\text{y}}^{\text{2}}\text{)(1}-{\text{z}}^{\text{2}}\text{)}}\)
- C.
  \(\frac{\text{x}}{\text{1}-{\text{x}}^{\text{2}}}+\frac{\text{y}}{\text{1}-{\text{y}}^{\text{2}}}+\frac{\text{z}}{\text{1}-{\text{z}}^{\text{2}}}=\frac{\text{4xyz}}{\text{(1}-{\text{x}}^{\text{2}}\text{)(1}-{\text{y}}^{\text{2}}\text{)(1}-{\text{z}}^{\text{2}}\text{)}}\)
- D.
  \(\frac{\text{x}}{\text{1}-{\text{x}}^{\text{2}}}+\frac{\text{y}}{\text{1}-{\text{y}}^{\text{2}}}+\frac{\text{z}}{\text{1}-{\text{z}}^{\text{2}}}=\frac{\text{xyz(x}+\text{y}+\text{z)}}{\text{(1}-{\text{x}}^{\text{2}}\text{)(1}-{\text{y}}^{\text{2}}\text{)(1}-{\text{z}}^{\text{2}}\text{)}}\)
Câu 4

Làm tính trừ \(x-1 -\frac{2}{x+1}\).
- A.
  \(\frac{{x}^{2}-3}{x+1}\)
- B.
  \(\frac{x+3}{x+1}\)
- C.
  \(\frac{{x}^{2}-3}{x-1}\)
- D.
  \(\frac{{x}^{2}+3}{x+1}\)
Câu 5

Làm tính trừ: \(\frac{12x}{x-9}-\frac{x-10}{81-{x}^{2}}\).
- A.
  \(\frac{12{x}^{2}+10x-9}{(x+3)(x-3)}\)
- B.
  \(\frac{12{x}^{2}+109x-9}{(x+3)(x-3)}\)
- C.
  \(\frac{12{x}^{2}+109x-10}{(x+9)(x-9)}\)
- D.
  \(\frac{12{x}^{2}-109x+10}{(x+9)(x-9)}\)
Câu 6

Thức hiện phép trừ phân thức \(\frac{3}{2x+6}-\frac{x-6}{2{x}^{2}+6x}\) được kết quả là
- A.
  \(-\frac{1}{x}\)
- B.
  \(\frac{1}{{x}^{2}}\)
- C.
  \(\frac{1}{x}\)
- D.
  \(-\frac{1}{{x}^{2}}\)
Câu 7

Thực hiện phép tính trừ: \(\frac{2x-1}{{x}^{2}+x}-x-1\).
- A.
  \(\frac{-{x}^{3}+2{x}^{2}+2x-1}{x(x+1)}\)
- B.
  \(\frac{-{x}^{3}-2{x}^{2}+x-1}{x(x+1)}\)
- C.
  \(\frac{{x}^{3}-2{x}^{2}+x-1}{x(x+1)}\)
- D.
  \(\frac{-{x}^{3}+{x}^{2}+x-1}{x(x+1)}\)
Câu 8

Làm tính trừ: \(\frac{x}{12{x}^{2}+6xy}-\frac{y}{4{x}^{2}+4xy+{y}^{2}}\).
- A.
  \(\frac{2x+5y}{3(2x+y{)}^{2}}\)
- B.
  \(\frac{2x-5y}{3(2x+y{)}^{2}}\)
- C.
  \(\frac{2x-5y}{6(2x+y{)}^{2}}\)
- D.
  \(\frac{2x+5y}{6(2x+y{)}^{2}}\)

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