5x+9: x+1

\(\Leftrightarrow\)5*(x+1)+4:x+1

\(\Rightarrow\)5*(x+1)\(⋮\)x+1

\(\Rightarrow\)4 \(⋮\)x+1

\(\Rightarrow\)x+1\(\in\)Ư(4) =\(\hept{\begin{cases}\\\end{cases}}\)1;2;4;-1;-2;-4

\(\Rightarrow\)x\(\hept{\begin{cases}\\\end{cases}}\)0;1;3;-2;-3;-5

Vậy x\(\in\)-----------------------

(5x + 9) : (x + 1)

<=> (5x + 5) + 4 : x+1

<=> 5(x+1) + 4 : x+1

<=>  4 : x+1

<=> x+1 thuộc Ư(4)

<=> x+1 thuộc { 1;-1;2;-2;4;-4}

<=> x+1 thuộc { 0;-2;-3;3;-5 }

dấu chia là dấu chia hết nha

\(B=\left(1+\frac{1}{2}\right).\left(1+\frac{1}{3}\right).\left(1+\frac{1}{4}\right)....\left(1+\frac{1}{99}\right)\)

     \(=\frac{3}{2}.\frac{4}{3}.\frac{5}{4}...\frac{100}{99}\)

      \(=\frac{3.4.5....100}{2.3.4...99}\)

Chúc bạn học tốt !

        \(=50\)

số số hạng: (100-1):1+1=100

tổng trên là: (100+1).100:2=5050

k nhoa

Tổng của dãy số đó là:

\(1+2+...+100=\left(100+1\right)\cdot\frac{100}{2}=5050\)

Đáp số:\(5050\)

5/6x+5/4=2

5/6x=3/4

x=9/10

\(\left(\frac{5}{6}x+\frac{5}{4}\right)\div\frac{3}{2}=\frac{4}{3}\)

\(\frac{5}{6}x+\frac{5}{4}=\frac{4}{3}\cdot\frac{3}{2}\)

\(\frac{5}{6}x+\frac{5}{4}=2\)

\(\frac{5}{6}x=2-\frac{5}{4}\)

\(\frac{5}{6}x=\frac{8}{4}-\frac{5}{4}\)

\(\frac{5}{6}x=\frac{3}{4}\)

\(x=\frac{3}{4}\div\frac{5}{6}\)

\(x=\frac{3}{4}\cdot\frac{5}{6}\)

\(x=\frac{1}{4}\cdot\frac{5}{2}\)

\(x=\frac{5}{8}\)

=1/2(2/1.3+2/3.5+2/5.7+....+2/2009.2011

=1/2(1/1-1/3+1/3-1/5+1/5-1/7+....+1/2009-1/2011

=1/2(1/1-1/2011)

=1/2.2010/2011

=1005/2011

=1/1-1/3+1/3-1/5+1/5-1/7+....+1/2009-2011

=1-1/2011

=2010/1011

x={0;1;2;3;4;5;6;7;8}

1/4.2/5-25.5/7

=1/10-125/7

=-1243/70

trả lời :
\(=\frac{1}{4}\times\frac{2}{5}-25\times\frac{7}{5}\)
\(=\frac{1}{10}-\frac{125}{7}\)

\(=\frac{-1243}{70}\)

hk tốt ~

ta có:\(=\frac{1}{2}.\left(\frac{2}{1.3}+\frac{2}{3.5}+\frac{2}{5.7}+...+\frac{2}{2009.2011}\right)\)

\(=\frac{1}{2}.\left(1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+...+\frac{1}{2009}-\frac{1}{2011}\right)\)

\(=\frac{1}{2}.\left(1-\frac{1}{2011}\right)\)

\(=\frac{1}{2}.\frac{2010}{2011}\)

\(=\frac{1005}{2011}\)

= 1/1-1/2+1/2-1/3+...+1/49-1/50

= 1/1-1/50

= 50/50-1/50

= 49/50 

Mà 1 = 50/50

Nên 49/50 < 50/50 

Vậy M < 1 

m=1/1.2+1/1.3 +...+1/49 .50 

=1-1/2+1/2-1/3+1/3-1/4+...+1/49-1/50

=1-1/50 <1 (vi1/50 >0)

17/20-9/8=-11/40

17/20-9/8=11/40