\(3\left(3x-\frac{1}{2}\right)^3+\frac{1}{9}=0\)

=> \(3\left(3x-\frac{1}{2}\right)^3=-\frac{1}{9}\)

=> \(\left(3x-\frac{1}{2}\right)^3=-\frac{1}{9}:3\)

=> \(\left(3x-\frac{1}{2}\right)^3=-\frac{1}{27}\)

=> \(\left(3x-\frac{1}{2}\right)^3=\left(-\frac{1}{3}\right)^3\)

=> \(3x-\frac{1}{2}=-\frac{1}{3}\)

=> \(3x=-\frac{1}{3}+\frac{1}{2}\)

=> \(3x=\frac{1}{6}\)

=> x = 1/6 : 3

=> x = 1/18

\(3\left(3x-\frac{1}{2}\right)^3+\frac{1}{9}=0\)

\(3.\left(3x-\frac{1}{2}\right)^3=\frac{-1}{9}\)

\(\left(3x-\frac{1}{2}\right)^3=\frac{-1}{27}=\left(\frac{-1}{3}\right)^3\)

\(3x-\frac{1}{2}=\frac{1}{3}\)

\(3x=\frac{5}{6}\)

\(x=\frac{5}{18}\)

Vậy...

Đề bài?

Đúng jui đó bn Hạ Ninh !!!

 bằng 2

1+1=2

hok tốt

phương anh###

Ta có: \(\frac{15}{90.94}+\frac{15}{94.98}+\frac{15}{98.102}+...+\frac{15}{146.150}\)

= \(15.\left(\frac{1}{90.94}+\frac{1}{94.98}+\frac{1}{98.102}+...+\frac{1}{146+150}\right)\)

= \(15.\left[\frac{1}{4}.\left(\frac{4}{90.94}+\frac{4}{94.98}+\frac{4}{98.102}+...+\frac{4}{146+150}\right)\right]\)

= \(15.\left[\frac{1}{4}.\left(\frac{1}{90}-\frac{1}{94}+\frac{1}{94}-\frac{1}{98}+\frac{1}{98}-\frac{1}{102}+...+\frac{1}{146}-\frac{1}{150}\right)\right]\)

= \(15.\left[\frac{1}{4}.\left(\frac{1}{90}-\frac{1}{150}\right)\right]\)

= \(15.\left(\frac{1}{4}.\frac{1}{225}\right)\)

= \(=\frac{1}{60}\)

Bài làm

   \(\frac{15}{90.94}+\frac{15}{94.98}+\frac{15}{98.102}+...+\frac{15}{146.150}\)

= \(15.\frac{1}{90.94}+15.\frac{1}{94.98}+15.\frac{1}{98.102}+...+15.\frac{1}{146.150}\)

= \(15.\left(\frac{1}{90.94}+\frac{1}{94.98}+\frac{1}{98.102}+...+\frac{1}{146.150}\right)\)

= \(15.\left(\frac{1}{90}-\frac{1}{94}+\frac{1}{94}-\frac{1}{98}+\frac{1}{98}-\frac{1}{102}+...+\frac{1}{146}-\frac{1}{150}\right)\)

= \(15.\left(\frac{1}{90}-\frac{1}{150}\right)\)

= \(15.\left(\frac{5}{450}-\frac{3}{450}\right)\)

= \(15.\frac{2}{450}\)

= \(\frac{2}{30}\)

# Chúc bạn học tốt #

ĐB\(\Leftrightarrow\frac{1}{x}=\frac{y-8}{8y}\)

\(\Leftrightarrow x\left(y-8\right)=8y\)

\(\Leftrightarrow\left(x-8\right)\left(y-8\right)=64\)

\(\Leftrightarrow x-8\inƯ\left(64\right)\)

Ta có bảng

Vậy (x;y) là (9;72),(10;40);(12;24);(16;16);(24;12);(40;10);(72;9)

\(B\inℤ\Leftrightarrow3n+11⋮2n-1\)

\(\Leftrightarrow n+12⋮2n-1\)

\(\Leftrightarrow2n+24⋮2n-1\)

\(\Leftrightarrow25⋮2n-1\)

\(\Leftrightarrow2n-1\inƯ\left(25\right)\)

Bạn tự giải tiếp nha!

Nhớ k cho mk đấy!

(2x+1)(y-3)=12

Vì x;y là số tự nhiên => 2x+1;y-3 là số tự nhiên

                                 => 2x+1;y-3 E Ư(12)

Ta có bảng:

Vậy cặp số tự nhiên (x;y) cần tìm là: (0;15) ; (1;7)

(2x + 1)(y - 3) = 12

=> 2x + 1;y - 3 thuộc Ư(12)

vì x là stn => 2x + 1 là stn, ta có bảng