cứ vẽ như vậy nè 

a) \(\dfrac{-15+9+11}{16}=\dfrac{5}{16}\)

b) \(\dfrac{2}{3}\left(1,4+1,6-1,2\right)=\dfrac{2}{3}\times\dfrac{9}{5}=\dfrac{6}{5}\)

c) \(3\dfrac{2}{15}\left(\dfrac{3}{5}+\dfrac{2}{5}\right)-\dfrac{31}{15}=\dfrac{47}{15}-\dfrac{31}{15}=\dfrac{16}{15}\)

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chép thiếu (⊙_⊙)？

A=1−2−3+4−5−6+7−8−9+....+2020−2021−2022D=1-2-3+4-5-6+7-8-9+....+2020-2021-2022

A =(1−2−3)+(4−5−6)+(7−8−9)+....+(2020−2021−2022)D=(1-2-3)+(4-5-6)+(7-8-9)+....+(2020-2021-2022)

A=(−4)+(−7)+(−10)+.....+(−2023)D=(-4)+(-7)+(-10)+.....+(-2023)

A=[(2023−4):3+1].[(−2023−4):2]D=[(2023-4):3+1].[(-2023-4):2]

A=674.(−1013,5)D=674.(-1013,5)

A=−683099

A=1−2−3+4−5−6+7−8−9+....+2020−2021−2022D=1-2-3+4-5-6+7-8-9+....+2020-2021-2022

A =(1−2−3)+(4−5−6)+(7−8−9)+....+(2020−2021−2022)D=(1-2-3)+(4-5-6)+(7-8-9)+....+(2020-2021-2022)

A=(−4)+(−7)+(−10)+.....+(−2023)D=(-4)+(-7)+(-10)+.....+(-2023)

A=[(2023−4):3+1].[(−2023−4):2]D=[(2023-4):3+1].[(-2023-4):2]

A=674.(−1013,5)D=674.(-1013,5)

A=−683099

\(\dfrac{1}{3}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{5}+...+\dfrac{1}{x}-\dfrac{1}{x+1}=\dfrac{1}{3}-\dfrac{x+1}{324}\)

\(\dfrac{1}{3}-\dfrac{1}{x+1}=\dfrac{1}{3}-\dfrac{x+1}{324}\)

\(\dfrac{1}{x+1}=\dfrac{x+1}{324}\)

\(\left(x+1\right)^2=324=18^2\)

\(\Leftrightarrow\left[{}\begin{matrix}x+1=18\\x+1=-18\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=17\\x=-19\end{matrix}\right.\)

Ta có \(\dfrac{1}{3.4}+\dfrac{1}{4.5}+\dfrac{1}{5.6}+...+\dfrac{1}{x\left(x+1\right)}=\dfrac{1}{3}-\dfrac{x+1}{324}\)

\(\Rightarrow\)\(\dfrac{4-3}{3.4}+\dfrac{5-4}{4.5}+\dfrac{6-5}{5.6}+...+\dfrac{\left(x+1\right)-x}{x\left(x+1\right)}=\dfrac{1}{3}-\dfrac{x+1}{324}\)

\(\Rightarrow\)\(\dfrac{1}{3}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{6}+...+\dfrac{1}{x}-\dfrac{1}{x+1}=\dfrac{1}{3}-\dfrac{x+1}{324}\)

\(\Rightarrow\)\(\dfrac{1}{3}-\dfrac{1}{x+1}=\dfrac{1}{3}-\dfrac{x+1}{324}\)

\(\Rightarrow\)\(\dfrac{1}{3}-\dfrac{1}{3}=-\dfrac{x+1}{324}+\dfrac{1}{x+1}\)

\(\Rightarrow\)\(\dfrac{1}{x+1}-\dfrac{x+1}{324}=0\)

\(\Rightarrow\)\(\dfrac{1}{x+1}=\dfrac{x+1}{324}\)

\(\Rightarrow\)(x+1).(x+1)=324

\(\Rightarrow\)(x+1)²=324

\(\Rightarrow\)(x+1)² = 18² = (-18)²

TH1: (x+1)² = 18²

\(\Rightarrow\)x+1 = 18 

\(\Rightarrow\)x = 17

TH2: (x+1)² = (-18)²

\(\Rightarrow\)x+1 = -18 

\(\Rightarrow\)x = -19

Vậy x\(\in\)\(\left\{17;-19\right\}\)

Ta có  (2022.19 + 152.3) - (2022.19 - 7.7)

= 2022.19 + 152.3 - 2022.19 + 7.7

= (2022.19 - 2022.19) + 456 + 49

= 0 + 505 = 505

bằng 160 bạn nhé

\(x+y+xy=40\)

\(x\left(1+y\right)+y=40\)

\(\left(x+1\right)\left(y+1\right)=41\)

Vì 41 là số nguyên tố nên xảy ra các trường hợp:

\(\left\{{}\begin{matrix}\left\{{}\begin{matrix}x+1=1\\y+1=41\end{matrix}\right.\\\left\{{}\begin{matrix}x+1=41\\y+1=1\end{matrix}\right.\\\left\{{}\begin{matrix}x+1=-1\\y+1=-41\end{matrix}\right.\\\left\{{}\begin{matrix}x+1=-41\\y+1=-1\end{matrix}\right.\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}\left\{{}\begin{matrix}x=0\\y=40\end{matrix}\right.\\\left\{{}\begin{matrix}x=40\\y=0\end{matrix}\right.\\\left\{{}\begin{matrix}x=-2\\y=-42\end{matrix}\right.\\\left\{{}\begin{matrix}x=-42\\y=-2\end{matrix}\right.\end{matrix}\right.\)