Trắc nghiệm Toán 8: Cộng, trừ các phân thức có lời giải chi tiết (phần 1)

A. $\frac{\text{A.C}}{\text{B}}$

B. $\frac{\text{A+C}}{\text{B}}$

C. $\frac{\text{A+C}}{{\text{B}}^2}$

D. $\frac{\text{A+C}}{\text{2B}}$

A. $\frac{\text{A}}{\text{B}}-\frac{\text{C}}{\text{D}}=\frac{\text{A}-\text{C}}{\text{B}-\text{D}}$

B. $\frac{\text{A}}{\text{B}}-\frac{\text{C}}{\text{D}}=\frac{\text{AD}}{\text{BC}}$

C. $\frac{\text{A}}{\text{B}}-\frac{\text{C}}{\text{D}}=\frac{\text{A}}{\text{B}}+\frac{-\text{C}}{\text{D}}$

D. $\frac{\text{A}}{\text{B}}-\frac{\text{C}}{\text{D}}=\frac{\text{A}-\text{C}}{\text{BD}}$

A. $\frac{-\text{3}}{\text{x}+\text{1}}$

B. $\frac{\text{x}+\text{1}}{\text{3}}$

C. $\frac{-\text{3}}{-\text{x}-\text{1}}$

D. $\frac{-\text{3}}{\text{x}-\text{1}}$

A. $\frac{\text{x}}{\text{x}-\text{1}}$

B. $\frac{\text{x}-\text{1}}{-\text{x}}$

C. $\frac{-\text{x}}{-\text{x}-\text{1}}$

D. $\frac{\text{x}}{-\text{x}+\text{1}}$

A. $\frac{-\text{1}}{\text{6xy}}$

B. $\frac{\text{1}}{{\text{6x}}^{\text{2}}\text{y}}$

C. $\frac{\text{1}}{\text{6xy}}$

D. $\frac{\text{x}}{\text{6xy}}$

A. -x

B. 2x

C. $\frac{x}{2}$

D. x

A. $\frac{\text{x}}{\text{x}+\text{1}}-\frac{\text{2}}{\text{x}+\text{1}}$

B. $\frac{\text{2x}}{\text{x}+\text{1}}-\frac{\text{2}}{\text{x}+\text{1}}$

C. $\frac{\text{x}}{\text{x}-\text{1}}+\frac{\text{1}}{\text{x}-\text{1}}$

D. $\frac{\text{x}}{\text{x}+\text{1}}+\frac{\text{1}}{\text{-x}-\text{1}}$

A. $\frac{{\text{x}}^{\text{2}}+\text{4}}{\text{x}-\text{2}}-\frac{\text{4x}}{\text{2}-\text{x}}$

B. $\frac{{\text{x}}^{\text{2}}+\text{4}}{\text{x}-\text{2}}+\frac{\text{4x}}{\text{2}-\text{x}}$

C. $\frac{\text{2x}}{\text{x}-\text{2}}+\frac{\text{4}}{{\text{x}}^{\text{2}}-\text{4}}$

D. $\frac{{\text{x}}^2}{\text{x}-\text{2}}-\frac{4}{\text{x-2}}$

A. -1

B. 1

C. $\frac{\text{a}-\text{b}}{\text{b}-\text{a}}$

D. $\frac{\text{a}+\text{b}-\text{4}}{\text{a}-\text{b}}$

A. $\frac{-\text{x}+\text{y}}{\text{xy}}$

B. $\frac{\text{x}-\text{y}}{\text{x}}$

C. $\frac{\text{x}-\text{y}}{\text{y}}$

D. $\frac{\text{x}-\text{y}}{\text{xy}}$

A. $\frac{\text{2x}-\text{9}}{{\text{x}}^{\text{2}}-\text{9}}$

B. $\frac{\text{2x}-\text{3}}{{\text{x}}^{\text{2}}-\text{9}}$

C. $\frac{\text{2x}-\text{9}}{\text{x}-\text{3}}$

D. $\frac{\text{x}-\text{6}}{{\text{x}}^{\text{2}}-\text{9}}$

A. $\frac{{\text{x}}^{\text{2}}+\text{2x}}{\text{(x}-\text{1)(x}+\text{1)}}$

B. 2

C. $\frac{{\text{2x}}^{\text{2}}+\text{2}}{\text{(x}-\text{1)(x}+\text{1)}}$

D. $\frac{{\text{2x}}^{\text{2}}}{{\text{x}}^{\text{2}}-\text{1}}$

A. $2x^2+5x-4$

B. $\frac{{\text{2x}}^{\text{2}}-\text{5x}-\text{4}}{\text{12x(x}-\text{1)(x}+\text{1)}}$

C. $2x^2-4x-4$

D. $2x^2-5x-4$

A. $\frac{-{\text{x}}^{\text{2}}+\text{15}}{\text{2(x}+\text{3)}}$

B. $\frac{{\text{x}}^{\text{2}}-\text{15}}{\text{2(x}+\text{3)}}$

C. $\frac{-{\text{x}}^{\text{2}}-\text{15}}{\text{2(x}+\text{3)}}$

D. Cả A, B, C đều sai

A. $\frac{\text{1}}{\text{x}+\text{2}}-\frac{\text{1}}{\text{(x}+\text{2)(4x}+\text{7)}}=\frac{\text{4x}}{\text{(x}+\text{2)(4x}+\text{7)}}$

B. $\frac{\text{2}-\text{21x}}{\text{18}}-\frac{\text{4}+\text{x}}{\text{12}}=\frac{\text{75x}-\text{16}}{\text{36}}$

C. $\frac{\text{1}}{\text{x}+\text{4}}-\frac{\text{1}}{\text{x}+\text{5}}=\frac{\text{1}}{\text{(x}+\text{4)(x}+\text{5)}}$

D. $\frac{\text{2}}{\text{x}-\text{5}}+\frac{\text{3x}}{{\text{x}}^{\text{2}}-\text{25}}=\frac{\text{4x}+\text{5}}{{\text{x}}^{\text{2}}-\text{25}}$

A. $\frac{\text{3x}-\text{4}}{{\text{4x}}^{\text{2}}{\text{y}}^{\text{5}}}+\frac{\text{9x}+\text{4}}{{\text{4x}}^{\text{2}}{\text{y}}^{\text{5}}}=\frac{\text{3}}{{\text{xy}}^{\text{4}}}$

B. $\frac{\text{2x}+\text{5}}{\text{3}}+\frac{\text{x}-\text{2}}{\text{3}}=\frac{\text{x}+\text{1}}{\text{3}}$

C. $\frac{\text{x}+\text{8}}{\text{x}-\text{1}}-\frac{\text{2x}-\text{1}}{\text{x}-\text{1}}-\frac{\text{6x}+\text{2}}{\text{x}-\text{1}}=\text{7}$

D. $\frac{\text{x}}{\text{x}-\text{y}}+\frac{\text{y}}{\text{x}+\text{y}}+\frac{{\text{2y}}^{\text{2}}}{{\text{x}}^{\text{2}}-{\text{y}}^{\text{2}}}=\frac{\text{x}+\text{y}}{\text{x}-\text{y}}$