Question

Answer 1

Bài 1:

\(a,=-\dfrac{2}{3}+\dfrac{1}{5}+\dfrac{1}{2}=\dfrac{1}{30}\\ b,=\dfrac{9}{10}\left(\dfrac{23}{11}-\dfrac{1}{11}+1\right)=\dfrac{9}{10}\cdot3=\dfrac{27}{10}\\ c,=\dfrac{4}{5}+\dfrac{4}{25}\cdot\dfrac{1}{4}-\dfrac{1}{5}\cdot1=\dfrac{4}{5}+\dfrac{1}{25}-\dfrac{1}{5}=\dfrac{16}{25}\\ d,=\dfrac{3^8\cdot2^{10}\cdot5^6}{2^9\cdot3^6\cdot5^7}=\dfrac{2\cdot3^2}{5}=\dfrac{18}{5}\)

Answer 2

Bài 4: 

a: Xét ΔOAD và ΔOCB có 

OA=OC

\(\widehat{O}\) chung

OD=OB

Do đó: ΔOAD=ΔOCB

Answer 3

mọi người chỉ mình bài 3,4,5 đuy mờ