Đặt A=2.2².2³.2⁴...2¹⁰⁰

2A=2(2.2².2³.2⁴...2¹⁰⁰)

2A=2².2³.2⁴...2¹⁰¹

2A-A=2¹⁰¹-2

A=2¹⁰¹-2/2

Động Từ :

Put , do , pick , go , get , have , study , sing , catch , dance

Danh từ :

dog , cat , hat , shirt , balloon , print , piano , bass , computer , maracas

10 động từ là:go,jum,sing,dance,sleep,water,wash,write,read,cry

9 danh từ là:flower,sand,family,home,house,book,pen,computer,clock

ks nhé!Học tốt!

\(I=1^2+2^2+3^2+4^2+...+2017^2+2018^2\)

\(I=\left(2^2-1^2\right)+\left(4^2-3^2\right)+...+\left(2018^2-2017^2\right)\)

\(I=\left(1+2\right)\left(2-1\right)+\left(3+4\right)\left(4-3\right)+...+\left(2017+2018\right)\left(2018-2017\right)\)

\(I=1+2+3+4+...+2017+2018\)

\(I=\frac{\left(2018+1\right).2018}{2}=2037171\)

I = 1² + 2² + 3² + ... + 2017²

= 1.1 + 2.2 + 3.3 + ... + 2017.2017

= 1.(2 - 1) + 2.(3 - 1) + 3.(4 - 1) + .... + 2017.(2018 - 1)

= 1.2 + 2.3 + 3.4 + ... + 2017.2018 - (1 + 2 + 3 + 4 + ... + 2017)

= 1.2 + 2.3 + 3.4 + ... + 2017.2018 - 2035153

Đặt K = 1.2 + 2.3 + 3.4 + ... + 2017.2018

=> 3K = 1.2.3 + 2.3.3 + 3.4.3 + .... + 2017.2018.3

=> 3K = 1.2.3 + 2.3.(4 - 1) + 3.4.(5 - 2) + ... + 2017.2018.(2019 - 2016)

=> 3K = 1.2.3 + 2.3.4 - 1.2.3 + 3.4.5 - 2.3.4 + .... + 2017.2018.2019 - 2016.2017.2018

=> 3K = 2017.2018.2019

=> K = 2017.2018.2019 : 3 

=> K = 2739315938

Lại có I = K - 2035153

= 2739315938 - 2035153

= 2 737 280 785

M = \(54-\frac{1}{2}\left(1+2\right)-\frac{1}{3}\left(1+2+3\right)-...-\frac{1}{12}\left(1+2+3+...+12\right)\)

\(54-\left(\frac{3}{2}+\frac{4}{2}+...+\frac{13}{2}\right)=54-\frac{1}{2}\left(3+4+5+...+13\right)=54-\frac{1}{2}.176=54-88\)

= -24

\(I=1\left(2-1\right)+2\left(3-1\right)+...+2017\left(2018-1\right)\)

\(I=\left(1.2+2.3+...+2017.2018\right)-\left(1+2+...+2017\right)\)

\(3I=\left(1.2.3+2.3\left(4-1\right)+...+2017.2018\left(2019-2016\right)\right)-\frac{3.2017.2018}{2}\)

=> \(I=\frac{2017.2018.2019}{3}-2017.1009\)

=> \(I=.....\)

dài :vv

a) \(\left|2x-5\right|=4\Leftrightarrow\hept{\begin{cases}2x-5=4\\2x-5=-4\end{cases}\Leftrightarrow\hept{\begin{cases}2x=9\\2x=1\end{cases}\Leftrightarrow}\hept{\begin{cases}x=\frac{9}{2}\\x=\frac{1}{2}\end{cases}}}\)

b) \(\frac{1}{3}-\left|\frac{5}{4}-2x\right|=\frac{1}{4}\)

\(\Leftrightarrow\left|\frac{5}{4}-2x\right|=\frac{1}{12}\Leftrightarrow\hept{\begin{cases}\frac{5}{4}-2x=\frac{1}{12}\\\frac{5}{4}-2x=-\frac{1}{12}\end{cases}\Leftrightarrow\hept{\begin{cases}2x=\frac{7}{6}\\2x=\frac{4}{3}\end{cases}}\Leftrightarrow\hept{\begin{cases}x=\frac{7}{12}\\x=\frac{2}{3}\end{cases}}}\)

Bài 1 :

a) \(|2x-5|=4\)

\(\Rightarrow\orbr{\begin{cases}2x-5=4\\2x-5=-4\end{cases}\Rightarrow}\orbr{\begin{cases}2x=9\\2x=1\end{cases}\Rightarrow\orbr{\begin{cases}x=\frac{9}{2}\\x=\frac{1}{2}\end{cases}}}\)

b) \(\frac{1}{3}-\left|\frac{5}{4}-2x\right|=\frac{1}{4}\)

\(\Rightarrow\left|\frac{5}{4}-2x\right|=\frac{1}{12}\)

\(\Rightarrow\orbr{\begin{cases}\frac{5}{4}-2x=\frac{1}{12}\\\frac{5}{4}-2x=-\frac{1}{12}\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}2x=\frac{7}{6}\\2x=\frac{4}{3}\end{cases}\Rightarrow\orbr{\begin{cases}x=\frac{7}{12}\\x=\frac{2}{3}\end{cases}}}\)

c) \(\left|\frac{-2}{3}\right|+\left|x-\frac{1}{3}\right|=\left|-1\right|-\left|\frac{-1}{3}\right|\)

\(\Rightarrow\frac{2}{3}+\left|x-\frac{1}{3}\right|=1-\frac{1}{3}\)

\(\Rightarrow\frac{2}{3}+\left|x-\frac{1}{3}\right|=\frac{2}{3}\)

\(\Rightarrow\left|x-\frac{1}{3}\right|=0\Rightarrow x-\frac{1}{3}=0\Rightarrow x=\frac{1}{3}\)

d) \(\left|-\frac{1}{2}\right|-\left|x+\frac{1}{4}\right|=\left|-\frac{3}{4}\right|\)

\(\Rightarrow\frac{1}{2}-\left|x+\frac{1}{4}\right|=\frac{3}{4}\)

\(\Rightarrow\left|x+\frac{1}{4}\right|=-\frac{1}{4}\)

Vì \(\left|x\right|\ge0\Rightarrow\)ko có gtri nào của x thỏa mãn đề bài

Bài 2 :

a) \(\left|x-1\right|=3x+2\)

\(\Rightarrow\orbr{\begin{cases}x-1=3x+2\\x-1=-3x-2\end{cases}\Rightarrow\orbr{\begin{cases}x-3x=2+1\\x+3x=-2+1\end{cases}}}\)

\(\Rightarrow\orbr{\begin{cases}-2x=3\\4x=-1\end{cases}\Rightarrow}\orbr{\begin{cases}x=\frac{-3}{2}\\x=\frac{-1}{4}\end{cases}}\)

b|) \(\left|9+x\right|=2x\Rightarrow\orbr{\begin{cases}9+x=2x\\9+x=-2x\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x-2x=-9\\x+2x=-9\end{cases}\Rightarrow\orbr{\begin{cases}-x=-9\\3x=-9\end{cases}\Rightarrow}\orbr{\begin{cases}x=9\\x=-3\end{cases}}}\)

c) \(\left|x+6\right|-9=2x\Rightarrow\left|x+6\right|=2x+9\)

\(\Rightarrow\orbr{\begin{cases}x+6=2x+9\\x+6=-2x-9\end{cases}\Rightarrow}\orbr{\begin{cases}x-2x=9-6\\x+2x=-9-6\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}-x=3\\3x=-15\end{cases}\Rightarrow\orbr{\begin{cases}x=-3\\x=-5\end{cases}}}\)

Cậu có thể tham khảo bài làm trên đây ạ, chúc cậu học tốt ^^

rất gấp và gấp rồi mn ơi

Chắc là bạn nên thêm hệ số vào trước K, chứ mik nhìn bài này cũng rối lắm

dễ thế mà

chỉ là tính thôi có j đâu

\(\left(\frac{-3}{4}+\frac{2}{5}\right):\frac{3}{7}+\left(\frac{3}{5}+\frac{-1}{4}\right):\frac{3}{7}\)

\(=\left(\frac{-3}{4}+\frac{2}{5}+\frac{3}{5}+\frac{-1}{4}\right):\frac{3}{7}\)

\(=\left[\left(\frac{-3}{4}+\frac{-1}{4}\right)+\left(\frac{2}{5}+\frac{3}{5}\right)\right]:\frac{3}{7}\)

\(=\left(-1+1\right):\frac{3}{7}\)

\(=0:\frac{3}{7}\)

\(=0\)

Học tốt

khó quá

a. Vì \(\left|x-y-5\right|\ge0\forall x;y;2019\left|y-3\right|^{2020}\ge0\forall y\)

\(\Rightarrow\left|x-y-5\right|+2019\left|y-3\right|^{2020}\ge0\)

Dấu "=" xảy ra \(\Leftrightarrow\orbr{\begin{cases}\left|x-y-5\right|=0\\2019\left|y-3\right|^{2020}=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x-y-5=0\\y-3=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x-y=5\\y=3\end{cases}}\)

b. \(2\left(x-5\right)^4\ge0\forall x;5\left|2y-7\right|^5\ge0\forall y\)

\(\Rightarrow2\left(x-5\right)^4+5\left|2y-7\right|^5\ge0\)

Dấu "=" xảy ra \(\Leftrightarrow\orbr{\begin{cases}2\left(x-5\right)^4=0\\5\left|2y-7\right|^5=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x-5=0\\2y-7=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=5\\y=\frac{7}{2}\end{cases}}\)