x = 1 nha bạn

ta có : (x + 1) + (x + 4) + (x + 7) +.........+ ( x + 31) + (x +34) =222. 
(x + x +....+ x) + (1+ 4+ 7 + ...+ 31 + 34) =222 
12x + 12.(1+34) :2 = 222 
12x + 210 = 222 => 12x=12 => x =1 

k mình nha!

đáp án là 1 nha

a)\(\frac{27}{5}\text{x}\frac{91}{12}\text{x}\frac{125}{9}\text{x}\frac{96}{13}=\frac{27}{9}\text{x}\frac{91}{13}\text{x}\frac{125}{5}\text{x}\frac{96}{12}=3\text{x}7\text{x}25\text{x}8\)

Đến đây tự tính nha !

b)\(\frac{2539}{35}\text{x}\frac{7}{90}+\frac{561}{35}\text{x}\frac{7}{90}=\frac{7}{90}\text{x}\left(\frac{2539}{35}+\frac{561}{35}\right)=\frac{7}{90}\text{x}\frac{3100}{35}=\frac{3100}{90}\text{x}\frac{7}{35}=\frac{310}{9}\text{x}\frac{1}{5}=\frac{62}{9}\)

1. 27/5 x 91/12 x 125/9 x 96/13

2. 2539/35 x 7/90 + 561/35 x 7/90

3. 31/7 : (2/5 x 31/7)

4. (29 x 15/23 x 36/29) : 5/23

3)\(\dfrac{31}{7}\) : (\(\dfrac{2}{5}\times\dfrac{31}{7}\) )

=\(\dfrac{31}{7}\) : \(\dfrac{2}{5}\times\dfrac{31}{7}\)

= \(\dfrac{31}{7}:\dfrac{31}{7}\times\dfrac{2}{5}\)

= \(\dfrac{2}{5}\)

4) (\(29\times\dfrac{15}{23}\times\dfrac{31}{7}\)) : \(\dfrac{5}{23}\) 

=\(29\times\dfrac{15}{23}\times\dfrac{31}{7}:\dfrac{5}{23}\)

= \(29\times\dfrac{31}{7}\times\dfrac{15}{23}:\dfrac{5}{23}\)

= 29 x \(\dfrac{31}{7}\times\dfrac{15}{23}\times\dfrac{23}{5}\)

= 29 x \(\dfrac{31}{7}\times3\)

= 29 x 3 x \(\dfrac{31}{7}\) 

= 87 x \(\dfrac{31}{7}\) 

= \(\dfrac{2697}{7}\)

11 x 13 x 15 x 17 + 23 x 25 x 27 x 29 + 31 x 33 x 35 x 37 + 45 x 47 x 49 x 51

=7096860

#Hok tốt!#

c/s 0

1) \(A=\frac{7}{10\times11}+\frac{7}{11\times12}+\frac{7}{12\times13}+...+\frac{7}{69\times70}\)

    \(A=7\times\left(\frac{1}{10\times11}+\frac{1}{11\times12}+\frac{1}{12\times13}+...+\frac{1}{69\times70}\right)\)

    \(A=7\times\left(\frac{1}{10}-\frac{1}{11}+\frac{1}{11}-\frac{1}{12}+\frac{1}{12}-\frac{1}{13}+...+\frac{1}{69}-\frac{1}{70}\right)\)

    \(A=7\times\left(\frac{1}{10}-\frac{1}{70}\right)\)

   \(A=7\times\frac{3}{35}\)

   \(A=\frac{3}{5}\)

2) \(B=\frac{1}{25\times27}+\frac{1}{27\times29}+\frac{1}{29\times31}+...+\frac{1}{73\times75}\)

    \(B=\frac{1}{2}\times\left(\frac{2}{25\times27}+\frac{2}{27\times29}+\frac{2}{29\times31}+...+\frac{2}{73\times75}\right)\).

    \(B=\frac{1}{2}\times\left(\frac{1}{25}-\frac{1}{27}+\frac{1}{27}-\frac{1}{29}+\frac{1}{29}-\frac{1}{31}+...+\frac{1}{73}-\frac{1}{75}\right)\)

    \(B=\frac{1}{2}\times\left(\frac{1}{25}-\frac{1}{75}\right)\)

    \(B=\frac{1}{2}\times\frac{2}{75}\)

    \(B=\frac{1}{75}\)

3) \(C=\frac{4}{2\times4}+\frac{4}{4\times6}+\frac{4}{6\times8}+...+\frac{4}{2008\times2010}\)

    \(C=\frac{4}{2}\times\left(\frac{2}{2\times4}+\frac{2}{4\times6}+\frac{2}{6\times8}+...+\frac{2}{2008\times2010}\right)\)

    \(C=2\times\left(\frac{1}{2}-\frac{1}{4}+\frac{1}{4}-\frac{1}{6}+\frac{1}{6}-\frac{1}{8}+...+\frac{1}{2008}-\frac{1}{2010}\right)\)

    \(C=2\times\left(\frac{1}{2}-\frac{1}{2010}\right)\)

    \(C=2\times\frac{502}{1005}\)

    \(C=\frac{1004}{1005}\)

_Chúc bạn học tốt_

cái gì đấy lỗi à

lỗi

Lỗi rồi nha! -_-

Câu này dễ x = 1

Không biết thì đừng chat

tách ra

\(1\)) \(5-\left(10-x\right)=7\)
\(10-x=5-7\)
\(10-x=-2\)
\(x=10-\left(-2\right)\)
\(x=12\)

\(2\)) \(-32-\left(x-5\right)=0\)
\(x-5=-32-0\)
\(x-5=-32\)
\(x=-32+5\)
\(x=-27\)

1)10-x=5-7

x=10-(-2)

x=12

2)x+5=0+32

x=32-5

x=27

3) -12+2x-9+x=0

-12+(2x+x-9)=0

3x-9=0+12

3x=12+9

x=21:3

x=7

4) 15-x=1-11

x=15-(-10)

x=25

5) 4-(27+3)=x-9

4-30=x-9

-26+9=x

x=-17

Dãy số 1,4,7,..........,31,34 có số số hạng là:

( 34 - 1 ) : 3 + 1 = 12 ( số )

Tổng dãy số 1,4,7,..............,31,34 là:

( 34 + 1 ) x 12 : 2 = 210

Sau đó bạn tự làm tiếp nha

Ta có : (x + 1) + (x + 4) + ..... + (x + 34) = 222

<=> (x + x + ..... + x) + (1 + 4 + ..... + 34) = 222

<=> 12x + 210 = 222

=> 12x = 12

=> x = 1