655 kb nha 

717

k mình nha

657 + 56 - 54 + 54 - 52 + 52 - 50 + 50 - 48=665

mọi người ủng hộ mik bằng cái

xin cảm ơn mọi người

chúc các bạn học tốt

72 x 48 + 74 x 48 + 72 x 52 + 28 x 52 

= 48 x ( 72 + 74 ) + 52 x ( 72 + 28 ) = 48 x 146 + 52 x 100 = 7008 + 5200 = 12208

a: =25x100-150=2500-150=2350

c: \(=520:\left\{515\cdot25\right\}\)

=104/2575

số số hạng có trong biểu thức trên là:

(58 - 40 ) : 1 + 1 = 19

=>( 40 - 41 ) + ( 42 - 43 ) + ... + ( 56 - 57 ) + 58

=> (-1) x  [( 19 - 1 ) : 2 ] + 58

=> (-1) x 9 + 58

=> (-9) + 58
=> 49
HT~~~

9*8*48+7*4*48+72*52+2*52*14

=72*48+28*48+72*52+28*52

=72 * ( 48 + 52 ) + 28 * ( 48 + 52 )

=72 * 100 + 28 * 100

=100 * ( 72 + 28 )

= 100 * 100

=10000

9 x 8 x 48 + 7 x 4 x 48 + 72 x 52 + 2 x 52 x 14 

= 72 x 48 + 28 x 48 + 72 x 52 + 2 x 14 x 52

= ( 72 + 28 ) x 48 + 72 x 52 + 28 x 52

= ( 72 + 28 ) x 48 + ( 72 + 28 ) x 52

=  100 x 48 + 100 x 52

= 100 x ( 48 + 52 )

= 100 x 100

= 10000

9 . 8 . 48 + 7 . 4 . 48 + 72 . 52 + 2 . 52 . 14

= 72 . 48 + 28 . 48 + 72 . 52 + 52 . 28

= 48 . ( 72 + 28 ) + 52 . ( 72 + 28 )

= 48 . 100 + 52 .100

= 100 . ( 48 + 52 )

= 100 . 100

= 10000

\(\frac{43-x}{57}+\frac{46-x}{54}=\frac{49-x}{51}+\frac{52-x}{48}\)

\(\Leftrightarrow\left(\frac{43-x}{57}+1\right)+\left(\frac{46-x}{54}+1\right)=\left(\frac{49-x}{51}+1\right)+\left(\frac{52-x}{48}+1\right)\)

\(\Leftrightarrow\frac{43-x+57}{57}+\frac{46-x+54}{54}=\frac{49-x+51}{51}+\frac{52-x+48}{48}\)

\(\Leftrightarrow\frac{100-x}{57}+\frac{100-x}{54}=\frac{100-x}{51}+\frac{100-x}{48}\)

\(\Leftrightarrow\frac{100-x}{57}+\frac{100-x}{54}-\left(\frac{100-x}{51}+\frac{100-x}{48}\right)=0\)

\(\Leftrightarrow\left(100-x\right)\left[\left(\frac{1}{57}+\frac{1}{54}\right)-\left(\frac{1}{51}+\frac{1}{48}\right)\right]=0\) (*)

Vì\(\frac{1}{57}< \frac{1}{51},\frac{1}{54}< \frac{1}{48}\Rightarrow\left(\frac{1}{57}+\frac{1}{54}\right)< \left(\frac{1}{51}+\frac{1}{48}\right)\)

\(\Rightarrow\left(\frac{1}{57}+\frac{1}{54}\right)-\left(\frac{1}{51}+\frac{1}{48}\right)< 0\)

Phương trình (*) xảy ra khi: \(100-x=0\Leftrightarrow x=100\)

Vậy phương trình có nghiệm duy nhất là x = 100

a)  2688

b)  41

c)  260

d)  - 23

a) - 72 . ( 15 - 49 ) + 15 . ( - 56 + 72 ) = -72 . -34 +15 . 16

                                                       = 2448 + 240

                                                       = 2688

b) 1532 + ( -168 ) + ( - 1432 ) + ( - 14 ) + 123 = 1364 + ( -1432) + ( -14) +123

                                                                 = -68 + ( -14 )  +123

                                                                 = -82 + 123 = 41

c) 75 - 5 . ( 15 - 40 ) - ( - 60 ) = 75 - 5 . (-25 )-(-60)

                                           = 75 - (-125) - ( -60 )

                                          = 200 - ( -60 ) = 260

d) | 31 -17 | - | 15 - 52 | = | 14 | - | -37 |

                                  = 14 - 37

                                  = -23

Phương trình đầu bài tương đương với 
\(\frac{x+43}{57}+1+\frac{x+46}{54}+1=\frac{x+49}{51}+1+\frac{x+52}{48}+1\)\(\Leftrightarrow\frac{x+43+57}{57}+\frac{x+46+54}{54}=\frac{x+49+51}{51}+\frac{x+52+48}{48}\)\(\Leftrightarrow\frac{x+100}{57}+\frac{x+100}{54}=\frac{x+100}{51}+\frac{x+100}{48}\)

\(\Leftrightarrow\orbr{\begin{cases}x+100=0\\\frac{1}{57}+\frac{1}{54}=\frac{1}{51}+\frac{1}{48}\left(sai\right)\end{cases}\Leftrightarrow x+100=0\Leftrightarrow x=-100}\)

Vậy phương trình có nghiệm duy nhất là x=-100

<=> \(\frac{x+43}{57}+1+\frac{x+46}{54}+1=\frac{x+49}{51}+1+\frac{x+52}{48}+1\)

<=> \(\frac{x+100}{57}+\frac{x+100}{54}=\frac{x+100}{51}+\frac{x+100}{48}\)

<=> \(\left(x+100\right)\left(\frac{1}{57}+\frac{1}{54}-\frac{1}{51}-\frac{1}{48}\right)=0\)

vi \(\frac{1}{57}< \frac{1}{51};\frac{1}{54}< \frac{1}{48}\Rightarrow\frac{1}{57}-\frac{1}{51}+\frac{1}{54}-\frac{1}{48}< 0\)

=> x+100=0 => x= -100

vay pt co nghiem \(x=-100\)

Ta thấy:\(\frac{x+43}{57}\)\(+\)\(\frac{x+46}{54}\)\(+\)\(2\)\(=\)\(\frac{x+49}{51}\)\(+\)\(\frac{x+52}{48}\)\(+\)\(2\)

\(\Rightarrow\)\(\frac{x+43}{57}\)\(+\)\(\frac{57}{57}\)\(+\)\(\frac{x+46}{54}\)\(+\)\(\frac{54}{54}\)\(=\)\(\frac{x+49}{51}\)\(+\)\(\frac{51}{51}\)\(+\)\(\frac{x+48}{52}\)\(+\)\(\frac{52}{52}\)

\(\Leftrightarrow\)\(\frac{x+100}{57}\)\(+\)\(\frac{x+100}{54}\)\(=\)\(\frac{x+100}{51}\)\(+\)\(\frac{x+100}{52}\)

\(\Leftrightarrow\)\((\)\(x+100)\)\((\frac{1}{57}\)\(+\)\(\frac{1}{54}\)\()\)\(=\)\((x+100)\)\((\frac{1}{52}\)\(+\)\(\frac{1}{51})\)

\(\Leftrightarrow\)\((x+100)\)\((\frac{1}{57}\)\(+\)\(\frac{1}{54}\)\(-\)\(\frac{1}{52}\)\(-\)\(\frac{1}{51}\)\()\)\(=\)\(0\)\((1)\)

Ta thấy: \(\frac{1}{57}\)< \(\frac{1}{52}\)

          \(\frac{1}{54}\)<\(\frac{1}{51}\)

\(\Rightarrow\)\(\frac{1}{57}\)\(+\)\(\frac{1}{54}\)< \(\frac{1}{52}\)\(+\)\(\frac{1}{51}\)

\(\Rightarrow\)\(\frac{1}{57}\)\(+\)\(\frac{1}{54}\)\(-\)\(\frac{1}{52}\)\(-\)\(\frac{1}{51}\)< 0 \((2)\)

Từ \((1)\)và \(\left(2\right)\)\(\Rightarrow\)\(x+100\)\(=0\)

\(\Leftrightarrow x=-100\)

Vậy phương trình có tập nghiệm \(x=-100\)