( 3x + 16 )\(⋮\)( x + 2 )

\(\Rightarrow\)3x + 16 = 3 ( x + 2 ) +10

\(\Rightarrow\)10\(⋮\)( x + 2 )

\(\Rightarrow\)x + 2 \(\in\)\(\left\{1;2;5;10\right\}\)

\(\Rightarrow\)x\(\in\left\{0;3;8\right\}\)

\(\left(3x+16\right)⋮x+2\)

\(\Rightarrow3\left(x+2\right)+10⋮x+2\)

\(\Rightarrow10⋮x+2\Rightarrow x+2\inƯ\left(10\right)\)

Mà \(Ư\left(10\right)=\left\{1;2;5;10\right\}\)

\(\Rightarrow x+2\in\left\{1;2;5;10\right\}\)

\(\Rightarrow x\in\left\{-1;0;3;8\right\}\)

Vì \(x\in N\Rightarrow x\in\left\{0;3;8\right\}\)

a) \(\left(4\frac{2}{3}-2\frac{2}{5}+7\frac{7}{13}\right)-\left(3\frac{5}{23}-6\frac{6}{13}\right)\)

=    \(4\frac{2}{3}-2\frac{2}{5}+7\frac{7}{13}-3\frac{5}{23}+6\frac{6}{13}\)

=     \(\left(4\frac{2}{3}-2\frac{2}{5}\right)+\left(7\frac{7}{13}+6\frac{6}{13}\right)-3\frac{5}{23}\)

=       \(2\frac{4}{15}+14-3\frac{5}{23}\)

=        \(16\frac{4}{15}-3\frac{5}{23}\)

=         \(13\frac{17}{345}\)

XIN LỖI NHA, MÌNH KO LÀM ĐƯỢC XONG CÂU b) , MONG BẠN THÔNG CẢM CHO MÌNH, KHI NÀO MÌNH NGHĨ RA CÂU b) MÌNH SẼ TRẢ LỜI

khó nhỉ 

\(21.7^2-11.7^2+90.7^2+49.125.16\)

\(=7^2.\left(21-11+90+49.16\right)\)

\(=...............................................\)

nha nguyenvankhoi196a

A=(5+5^2+5^3+5^4)+(5^5+5^6+5^7+5^8)+.......+(+5^93+5^94+5^95+5^96)

=5(1+5+25+125)+5^5(1+5+25+125)+.......+5^93(1+5+25+125)

=5.156+5^5.156+...............+5^93.156\(⋮\)156

tách 4 số liên tiếp ra thành 5(1+5+5^2+5^3)+...+5^93(1+5+5^2+5^3)=156(5+...+5^93)

\(\frac{4^6.9^5+6^9.120}{8^4.3^{12}-6^{11}}\)= \(\frac{4096.59049+10077696.120}{4096.531441-362797056}\)= \(\frac{241864704+1209323520}{2176782336-362797056}\)= \(\frac{1451188224}{1813985280}\)