`@` `\text {Ans}`

`\downarrow`

`a,`

`(x-1954) \times 5=50`

`x-1954 = 50 \div 5`

`x-1954 = 10`

`x=10 + 1954`

`x= 1964`

`B.`

`48 - 40 \times x=8`

`40 \times x=48-8`

`40 \times x = 40`

` x=40 \div 40`

`x=1`

`C.`

`2+70 \div x = 3`

`70 \div x = 3-2`

`70 \div x = 1`

`x=70 \div 1`

`x=70`

`D. [3 \times (x+2) \div 7]  \times  4=120`

`3 \times (x+2) \div 7 = 120 \div 4`

`3 \times (x+2) \div 7 =30`

`3 \times (x+2) = 30 \times 7`

`3 \times (x+2)=210`

`x+2=210 \div 3`

`x+2=70`

`x=70-2`

`x=68`

`E.`

`7,2 \div [ (0,6 \times x+8) \div 20 + 59] = 0,12?` Thiếu ngoặc bạn nhé._.

\(a,\left(x-1954\right)\times5=50\\ x-1954=50:5\\ x-1954=10\\ x=1954+10\\ x=1964\\b.48-40\times x=8\\40\times x=48-8\\40\times x=40\\ x=40:40\\ x=1 \\ c.2+70:X=3\\ 70:x=3-2\\ 70:x=1\\ x=70:1\\ x=70\\ d,\left[3\times\left(x+2\right):7\right]\times4=120\\ 3\times\left(x+2\right):7-120:4\\ 3\times\left(x+2\right):7=30\\ \left(x+2\right):7=30:3\\ \left(x+2\right):7=10\\ x+2=10\times7\\ x+2=70\\ x=70-2\\ x=68\)

Bài 4:

a: =>7/x-5=2

=>x-5=7/2

=>x=17/2

b: =>1-2x=-5

=>2x=6

=>x=3

c: =>2x-3=5 hoặc 2x-3=-5

=>2x=8 hoặc 2x=-2

=>x=-1 hoặc x=4

d: =>2(x+1)^2+17=21

=>2(x+1)^2=4

=>(x+1)^2=2

=>\(x+1=\pm\sqrt{2}\)

=>\(x=\pm\sqrt{2}-1\)

mình lớp 6 nên câu d ko hiểu cách đó

=>2.(x-1)^2=120-48

=>2.(x-1)^2=72

=>(x-1)^2=72:2

=>(x-1)^2=36

=>(x-1)^2=6^2

=>x-1=6

=>x=6+1

=>x=7

giúp mình nhé

giúp mình đi

a) 13 x ( x +1 ) =143

x+1= 143 : 13

x+1= 11

x= 11-1

x= 10

b) ( x - 2 ) : 7 = 12

x-2= 12 x 7

x-2=84

x=84+2

x=86

c) 120 : ( x - 3 )= 8

x-3=120:8

x-3=15

x=15+3

x=18

Ghi lời giải nha mọi người

a) 120:{50.50:[450 - (4.125 - 4.25)]}
=  120:{50.50:[450 - (4.25.5 - 4.25)]}
=  120:{50.50:[450 - (4.25(5 - 1))]}
=  120:{50.50:[450 - (100.4)]}
=  120:{50.50:[450 - 400]}
=  120:{50.50:50}
=  120:50
=  12/5

a) (2x - 4)(48 - 12x) = 0
=> 2(x - 2).12(4 - x) = 0
=> (x - 2)(4 - x) = 0 (2 và 12 khác 0)
=> x - 2 = 0      hay      4 - x = 0
=> x      = 2      I    =>       x = 4

b)  134 - 2{156 - 6[54 - 2(9 + 6)]}x = 86
=> 134 - 2{156 - 6[54 - 2.15]}x      = 86
=> 134 - 2{156 - 6[54 - 30]}x         = 86
=> 134 - 2{156 - 6.24}x                = 86
=> 134 - 2{12.13 - 12.2.6}x           = 86
=> 134 - 2{12[13 - 2.6]}x              = 86
=> 134 - 2{12[13 - 12]}x               = 86
=> 134 - 2{12.1}x                        = 86
=> 134 - 2.12x                            = 86
=> 134 - 24x                               = 86
=>         24x                               = 48
=>            x                                = 2

a, x = 384

b, x = 161

c, x = 8

d, x = 15

X