=(7/3+17/5)*4/3=86/15*4/3=344/45

1A

2C

3C

4B

7D

8B

bài đou ?

\(\left(\dfrac{\sqrt{x}}{\sqrt{x}-1}-\dfrac{1}{x-\sqrt{x}}\right):\left(\dfrac{1}{\sqrt{x}+1}+\dfrac{2}{x-1}\right)\\ =\left(\dfrac{\sqrt{x}}{\sqrt{x}-1}-\dfrac{1}{\sqrt{x}\left(\sqrt{x}-1\right)}\right):\left(\dfrac{1}{\sqrt{x}+1}+\dfrac{2}{\left(\sqrt{x}-1\right)\left(\sqrt{x}+1\right)}\right)\\ =\left(\dfrac{\sqrt{x}\cdot\sqrt{x}}{\sqrt{x}\left(\sqrt{x}-1\right)}-\dfrac{1}{\sqrt{x}\left(\sqrt{x}-1\right)}\right):\left(\dfrac{\sqrt{x}-1}{\left(\sqrt{x}+1\right)\left(\sqrt{x}-1\right)}+\dfrac{2}{\left(\sqrt{x}-1\right)\left(\sqrt{x}+1\right)}\right)\\ =\dfrac{x-1}{\sqrt{x}\left(\sqrt{x}-1\right)}:\dfrac{\sqrt{x}+1}{\left(\sqrt{x}-1\right)\left(\sqrt{x}+1\right)}\)

\(=\dfrac{x-1}{\sqrt{x}\left(\sqrt{x}-1\right)}\cdot\dfrac{\left(\sqrt{x}-1\right)\left(\sqrt{x}+1\right)}{\sqrt{x}+1}\\ =\dfrac{x-1}{\sqrt{x}}\)

https://edward29.github.io/surprise/

Câu 6

a) Ta có: \(\widehat{A}=90^0\) ⇒a⊥c

a//b, a⊥c ⇒b⊥c

b) Ta lại có: M₁+N₁=180⁰(trong cùng phía)

120⁰+N₁=180⁰

N₁=180⁰-120⁰=60⁰

\(\dfrac{x}{30}=\dfrac{3}{5}+\dfrac{7}{30}\)

\(\dfrac{x}{30}=\dfrac{18}{30}+\dfrac{7}{30}\)

\(\dfrac{x}{30}=\dfrac{25}{30}\)

=> x=25

x =25 nha bạn

25