Answer:

\(7,46 : 0,25 + 14,92 + 7,46 : 0,5 + 7,46 × 2\)

\(=7,46×4+7,46×2+7,46×2+7,46×2\)

\(=7,46×(4+2+2+2)\)

\(=74,6\)

dễ mà

2,54 × x + 7,46 × x = 30

x x ( 2,54 + 7,46 ) = 30

x x 10                    = 30

x                            = 30 : 10

x                             = 3

2,54 × x + 7,46 × x = 30

=> x ×  (2,54 + 7,46) = 30

=> x ×  10 = 30

=> x = 30 : 10

=> x = 3

vậy_

x(2,54+7,46)=30

X.10=30

X=30:10

X=3

X 5   +   5 N a O H   →   m u o i   +   H 2 O

a  →   5a                →       a

Bảo toàn khối lượng:  m p e p t i t   +   m N a O H   =   m m u o i   +   m H 2 O    

→ 7,46 + 5a.40 = 11,1 + 18a → a = 0,02

X 5   +   4 H 2 O   +   5 H C l   →   m u o i

Bảo toàn khối lượng :  m p e p t i t   +   m H 2 O   +   m H C l   =   m m u o i

→  m m u o i   =   7 , 46   +   4.0 , 02.18   +   5.0 , 02.36 , 5   =   12 , 55

Đáp án cần chọn là: A

Chọn đáp án D

Gọi số mol của X là a mol → n N a O H = 5a mol và n H 2 O = b mol

Bảo toàn khối lương ta có 7,46 + 5a. 40 = 11,1 + 18a → a = 0,02

Khi thủy phân X bằng dung dịch HCl → n H C l = 5a = 0,1 mol, n H 2 O = 4a = 0,08 mol

dễ ấy mà

1. \(x-8+32=68\)

\(x-8=68-32\)

\(x-8=36\)

\(x=36+8\)

\(x=44\)

_____

2. \(x+8+32=68\)

\(x+8=68-32\)

\(x+8=36\)

\(x=36-8\)

\(x=28\)

_____

3. \(98-x+34=43\)

\(98-x=43-34\)

\(98-x=9\)

\(x=98-9\)

\(x=89\)

_____

4. \(98+x-34=43\)

\(98+x=43+34\)

\(98+x=77\)

\(x=77-98\)

\(x=-21\)

_____

5. \(x:5:4=800\)

\(x:5=800.4\)

\(x:5=3200\)

\(x=3200.5\)

\(x=16000\)

_____

6. \(18+x=384:8\)

\(18+x=48\)

\(x=48-18\)

\(x=30\)

_____

7. \(\left(84,6-2\times x\right):3,02=5,1\)

\(84,6-2.x=5,1.3,02\)

\(84,6-2.x=15,402\)

\(2.x=84,6-15,402\)

\(2.x=69,198\)

\(x=69,198:2\)

\(x=34,599\)

_____

8. \(x\times5=120:6\)

\(x.5=20\)

\(x=20:5\)

\(x=4\)

_____

9. \(\left(15\times24-x\right):0,25=100:0,25\)

\(\left(15.24-x\right):0,25=400\)

\(15.24-x=400.0,25\)

\(15.24-x=100\)

\(360-x=100\)

\(x=360-100\)

\(x=260\)

1,x-8+32=68

=>x-8=68-32=36

=>x=36+8=42

2,x+8+32=68

=>x+8=68-32=36

=>x=36-8=28

3,98-x+34=43

=>98-x=43-34=9

=>x=98-9=89

4,98+x-34=43

=>98+x=43+34=77

=>x=77-98=-21

5,x:5:4=800

=>x:20=800

=>x=800x20=16000

6,18+x=384:8=48

=>x=48-18=30

7,(84,6-2x):3,02=5,1

=>84,6-2x=5,1x3,02=15,402

=>2x=84,6-15,402=69,198

=>x=69,198:2=34,599

8,5x=120:6=20

=>x=20:5=4

9,(15x24-x):0,25=100:0,25=400

=>360-x=400x0,25=100

=>x=360-100=260.

1. \(...\Rightarrow x+24=68\Rightarrow x=68-24=44\)

2. \(...\Rightarrow x+40=68\Rightarrow x=68-40=28\)

3. \(...\Rightarrow3^{2\left(8+x\right)}=9=3^2\Rightarrow2\left(8+x\right)=2\Rightarrow8+x=1\Rightarrow x=-7\)

4. \(...\Rightarrow3^{2\left(8+x\right)}=77\) (bạn xem lại đề)

5. \(...\Rightarrow x:5=800.4\Rightarrow x:5=3200\Rightarrow x=3200.5=16000\)

6. \(...\Rightarrow18+x=48\Rightarrow x=48-18=30\)

7. \(...\Rightarrow84,6-2x=5,1.3,02=15,402\Rightarrow2x=84,6-15,402\Rightarrow2x=69,198\Rightarrow x=34,599\)

8. \(...\Rightarrow5.x=20\Rightarrow x=20:5=4\)

9. \(\left(360-x\right):0,25=400\Rightarrow360-x=400.0,25=100\Rightarrow x=400-100=300\)

x:0,25+x:0,25+x:1/8+xx6=62,5

=x:0,25+x:0,25+Xx0,125+Xx6=62,5

=Xx4+Xx4+Xx8+Xx6

=Xx24=62,5

X=62,5:24

X=125/48

X : 0,5 + X : 0,25 + X : 1/8 + X x 6 = 62,5

X : 1/2 + X : 1/4 + X : 1/8 + X x 6 = 62,5

X x 2 + X x 4 + X x 8 + X x 6 =62,5

X x ( 2+4+8+6 ) = 62,5

X x 20 = 62 ,5

X         = 62,5 : 20 

X         = 3,125

\(x\div\left(0,5+0,25+\frac{1}{8}\right)+x\times6=62,5\)

\(x\div0,875+x\times6=62,5\)

\(x\times\frac{8}{7}+x\times6=62,5\)

\(x\times\left(\frac{8}{7}+6\right)=62,5\)

\(x\times\frac{50}{7}=62,5\)

\(x=62,5\div\frac{50}{7}\)

\(x=62,5\times\frac{7}{50}\)

\(x=8,75\)

=>10y=19/8

hay y=19/80

=15

4 × 25 × 0,25 × \(\dfrac{1}{5}\) × \(\dfrac{1}{2}\) × 6

= 100 × 0,25 × 0,2 × 0,5 x 6

= 25 × 0,1 × 6

= 2,5 × 6

= 15