\(\left(x+1233\right)-1978=9876\)

\(\Leftrightarrow x+1233=9876+1978\)

\(\Leftrightarrow x+1233=11854\)

\(\Leftrightarrow x=11854-1233\)

\(\Leftrightarrow x=10621\)

x+1233-1978=9876

x                 =(9876+1987)-1233

x                 =10630

\(\left(x+1233\right)-1978=9876\)

\(\Rightarrow\left(x+1233\right)=9876+1978\)

\(\Rightarrow\left(x+1233\right)=11854\)

\(\Rightarrow x=11854-1233\)

\(\Rightarrow x=10721\)

phân tích ra cái j vậy

x : 637 = 2345

=>x= 2345 x 637

=> x =1493765

4000 - x =138

=> x =4000 - 138

=> x = 3862

212552 : x = 326

=>x = 212552 : 326

=> x =652

( x + 1233 ) - 1978 = 9876

=>(x+1233) = 11854

=> x =10621

x : 2 : 3 = 138

=>x:2 = 138 . 3 = 414

=> x = 828

x : 637 = 2345

<=> x = 2345 . 637

<=> x = 1493765

#hoc_tot#

Đáp án là A

x - 5678 = 9876

x             =9876+5678

x              =15554

=> chọn ý A . 15554 nhé !!

X x 5 + 1111 = 9876

X x 5 = 9876 - 1111

X x 5 = 8765 

x = 8765 : 5

x = 1753

X x 5 = 8765

X = 8765 : 5

X =1753

x*5+1111=9876

x*5=9876-1111

x*5=8765

x=1753

23456+12345=12345+23456

1234+2345=9786-6207

\(23456+12345=12345+x\)

\(=35801\)

\(=35801-12345\)

\(=23456\)

\(1234+2345=9876-x\)

\(=3579\)

\(=9876-3579\)

\(=6297\)

23456 + 12345 = 12345 + x 

12345 + x = 23456 + 12345

12345 + x = 35801

             x = 35801 - 12345 

             x = 23456

1234 + 2345 = 9876 - x

9876 - x = 1234 + 2345

9876 - x = 3579

          x = 9876 - 3579

          x = 6297

a) 2412787

b) 55543

x=105

x*6,5+x*3,5=20

Lời giải:

a. $121-3(x-5)=6$

$3(x-5)=121-6=115$

$x-5=115:3=\frac{115}{3}$

$x=\frac{115}{3}+5=\frac{130}{3}$

b.

$2x-138=2^3.3^2=72$

$2x=72+138=210$

$x=210:2=105$

c.

$x-3\vdots 7$

$\Rightarrow x-3\in\left\{0;7;14;21;28;35;42;49; 56;...\right\}$

Mà $10< x< 50$ nên $x\in\left\{14;21;28;35;42;49\right\}$

d.

$27\vdots x+1$

$\Rightarrow x+1\in\left\{\pm 1; \pm 3; \pm 9; \pm 27\right\}$

$\Rightarrow x\in\left\{0; -2; -4; 2; 8; -10; 26; -28\right\}$

a ) 121-3.(x - 5 ) = 6

3.(x-5) = 121 -6

3. (x-5)=115

x-5  = 115:3

x-5=35

x=35+5

x = 40

b) 2x - 138 = 2'3. 3'2

2x -138=8.9

2x-138=72

2x=72+138

2x=210

x=210:2

x=105

c) theo bài ra : x-3 ∈ B(7)

ta có B(7)=(0,7,14,21,28,35,49,56,...)

=) x-3 ∈ ( 0,7,14,21,28,35,49,56,...)

=) x ∈( 3 , 10,17,24,31,38,42,58,..)

mà 10 <x<50 nên x ∈ ( 17 , 24 ,31,38,42 )

vậy x ∈(17,24,31,38,42)

Lời giải:

a. $121-3(x-5)=6$

$3(x-5)=121-6=115$

x-5=115:3=\frac{115}{3}x−5=115:3=3115​

x=\frac{115}{3}+5=\frac{130}{3}x=3115​+5=3130​

b.

2x-138=2^3.3^2=722x−138=23.32=72

$2x=72+138=210$

$x=210:2=105$

c.

$x-3⋮7$

$\Rightarrow x-3\in \left\{0;7;14;21;28;35;42;49;56;...\right\}$

Mà $10<x<50$ nên $x\in \left\{14;21;28;35;42;49\right\}$

d.

$27⋮x+1$

$\Rightarrow x+1\in \left\{\pm 1;\pm 3;\pm 9;\pm 27\right\}$

$\Rightarrow x\in \left\{0;-2;-4;2;8;-10;26;-28\right\}$

\(70-5\cdot\left(x-3\right)=45\)

\(\Rightarrow5\cdot\left(x-3\right)=70-45\)

\(\Rightarrow5\cdot\left(x-3\right)=25\)

\(\Rightarrow x-3=\dfrac{25}{5}\)

\(\Rightarrow x-3=5\)

\(\Rightarrow x=5+3=8\)

==============

\(10+2\cdot x=4^5:4^3\)

\(\Rightarrow10+2\cdot x=4^2\)

\(\Rightarrow10+2\cdot x=16\)

\(\Rightarrow2\cdot x=16-10\)

\(\Rightarrow2\cdot x=6\)

\(\Rightarrow x=\dfrac{6}{2}=3\)

=============

\(2\cdot x-138=2^3\cdot3^2\)

\(\Rightarrow2\cdot x-138=72\)

\(\Rightarrow2\cdot x=72+138\)

\(\Rightarrow2\cdot x=210\)

\(\Rightarrow x=\dfrac{210}{2}=105\)

==============

\(231-\left(x-6\right)=1339:12\)

\(\Rightarrow231-x+6=1339:12\)

\(\Rightarrow237-x=\dfrac{1339}{12}\)

\(\Rightarrow x=237-\dfrac{1339}{12}\)

\(\Rightarrow x=\dfrac{1505}{12}\)