Question

Tổng \(\dfrac{a}{b}+\dfrac{-a}{b+1}\) bằng :

(A) \(\dfrac{a}{b\left(b+1\right)}\)                                    (B) \(0\)

(C) \(\dfrac{1}{b\left(b+1\right)}\)                                    (D) \(\dfrac{2ab+1}{b\left(b+1\right)}\)

Hãy chọn đáp đúng ?

Answer 1

đáp án đúng là A nha

tích nha^^

Answer 2

\(\dfrac{a}{b}+\dfrac{-a}{b+1}=a\left(\dfrac{1}{b}-\dfrac{1}{b+1}\right)=\dfrac{a}{b\left(b+1\right)}\)
Đáp án: C

Answer 3

\(\dfrac{a}{b}+\dfrac{-a}{b+1}=a\left(\dfrac{1}{b}-\dfrac{1}{b+1}\right)=\dfrac{1}{b\left(b+1\right)}\)

=> Đáp án C

Answer 4

Ta có:\(\dfrac{a}{b}+\dfrac{-a}{b+1}=\dfrac{a}{b}-\dfrac{a}{b+1}=a\left(\dfrac{1}{b}-\dfrac{1}{b+1}\right)=a\dfrac{1}{b\left(b+1\right)}=\dfrac{a}{b\left(b+1\right)}\)

\(\)Đáp án đúng là A