1, \(\left(y+7\right)\left(y-5\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}y+7=0\\y-5=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}y=-7\\y=5\end{matrix}\right.\)

2, \(25-\left(30+x\right)=\left(-24+3\right)\)

\(\Rightarrow25-\left(30+x\right)=-21\)

\(\Rightarrow30+x=25-\left(-21\right)\)

\(\Rightarrow30+x=25+21\)

\(\Rightarrow30+x=46\)

\(\Rightarrow x=46-30\)

\(\Rightarrow x=16\)

1. y = -7,5

2. x = 16

bạn đã kiểm tra kĩ chưa vậy?mình đọc đề câu B mà loạn não luôn á;-;

mik kiểm tra rùi

1.

a) \(2^x=128\)

\(2^x=2^7\)

\(=>x=7\)

b) \(8^{x-1}=64\)

\(8^{x-1}=8^2\)

\(=>x-1=2\)

\(x=2+1\)

\(=>x=3\)

c) \(3+3^x=30\)

\(3^x=30-3\)

\(3^x=27=3^3\)

\(=>x=3\)

d) \(\left(x+2\right)=64\) -> đề có thiếu không vậy?

e) \(3^2.x=3^5\)

\(x=3^5:3^2\)

\(=>x=3^3=27\)

f) \(\left(2x-1\right)^3=343\)

\(\left(2x-1\right)^3=7^3\)

\(=>2x-1=7\)

\(2x=7+1\)

\(2x=8\)

\(x=8:2\)

\(=>x=4\)

\(#Wendy.Dang\) 

a,\(2^x\)=128           b,\(8^{x-1}\)=64              c,3+\(3^x\)=30           d,x+2=64

\(2^7\)=128               \(8^{x-1}\)=\(8^2\)                 \(3^x\)=30-3                  x=64-2

=>x=7              =>x-1=2                  \(3^x\)=27                      x=62

                         x=2+1=3                \(3^x\)=\(3^3\)

                                                     =>x=3

e,\(3^2\).x=\(3^5\)                             f,(2x-\(1^3\))=343

x=\(3^5\):\(3^2\)                                 2x=1+343

x=27                                     2x=344

                                               x=344:2

                                               x=172

       \(\frac{2}{5}\times\frac{1}{2}-\frac{2}{5}\times\frac{1}{3}-\frac{2}{5}\times\)\(\frac{1}{6}\)

\(=\frac{2}{5}\times\left(\frac{1}{2}-\frac{1}{3}-\frac{1}{6}\right)\)

\(=\frac{2}{5}\times\frac{0}{6}\)

\(=\frac{2}{5}\times0\)

\(=0\)

\(\frac{2}{5}\times\frac{1}{2}-\frac{2}{5}\times\frac{1}{3}-\frac{2}{5}\times\frac{1}{6}\)

\(=\frac{2}{5}\times\left(\frac{1}{2}-\frac{1}{3}-\frac{1}{6}\right)\)

\(=\frac{2}{5}\times0\)

\(=0\)

\(\frac{2}{5}\times\frac{1}{2}-\frac{2}{5}\times\frac{1}{3}-\frac{2}{5}\times\frac{1}{6}\)

\(=\frac{2}{5}\times\left(\frac{1}{2}-\frac{1}{3}-\frac{1}{6}\right)\)

\(=\frac{2}{5}\times\left(\frac{3}{6}-\frac{2}{6}-\frac{1}{6}\right)\)

\(=\frac{2}{5}\times0\)

\(=0\)

Học tốt

a) -12x + 60 + 21 - 7x =15

-12x - 7x + 81 = 15

-19x = 15 - 81

-19x = -66

x= -66 : (-19)

x = \(\frac{66}{19}\)

Vậy x = \(\frac{66}{19}\)

b) 30x + 60 - 6x + 30 - 24x= 100

30x - 6x - 24x + 60 +30= 100

x ( 30 - 6- 24 ) + 90 = 100

x. 0 + 90 =100

x. 0 =10 ( vô lý )

\(\Rightarrow\) x \(\in\phi\)

k đi mình lamf cho

,làm ơn giúp mik với ah

\(\left(1+\dfrac{2}{3}\right).\left(1+\dfrac{2}{4}\right).\left(1+\dfrac{2}{5}\right)....\left(1+\dfrac{2}{2020}\right).\left(1+\dfrac{2}{2021}\right)\)

= \(\dfrac{5}{3}.\dfrac{6}{4}.\dfrac{7}{5}.\dfrac{8}{6}.\dfrac{9}{7}....\dfrac{2022}{2020}.\dfrac{2023}{2021}\)

= \(\dfrac{1}{3}.\dfrac{1}{4}.2022.2023\)

= \(\dfrac{337.2023}{2}\)

= \(\dfrac{\text{681751}}{2}\)

VD: 1/2 là 1 phần 2 đó nha.

a: x/3-1/6=1/5

=>x/3=11/30

hay x=11/90

b: =>1/2x=2

hay x=4

c: =>2/3:x=-7-1/3=-22/3

=>x=-1/11

a: x/3-1/6=1/5

=>x/3=11/30

hay x=11/90

b: =>1/2x=2

hay x=4

c: =>2/3:x=-7-1/3=-22/3

=>x=-1/11

a) 10 - x : 2 = 1

x: 2 = 9

x = 18

b) x:4 + 3 x 2 = 7

x:4 + 6 = 7

x:4 = 1

x = 4

c) 2: x + 5 = 6

2: x = 1

x = 2

+4.10-x:2=1

40-x:2=1

     x:2=40-1

     x:2=39

    x:2=19,5

+5.x:4+3*2=7

5.x:4+6=7

5.x:4=7-6=1

5.x=1.4=4

x=4:5

x=0,8

+6.2:x+5=6

12:x=6-5

12:x=1

x=12:1

x=12

+7.2*x*3*5=30

14.x.15=30

14.x=2

x=2:14

x=1/7

+8.2*x:10*2=1

16.x:20=1

16.x=20

x=20:16

x=1,25

9.18:x-5*2=8

10.5*5-2:x=24

d) 2 * x * 3 * 5 = 30

x * 30 = 30

x = 1

e) 2 * x : 10* 2 = 1

2*x * 1/10 * 2 = 1

2/5 * x = 1

x = 5/2

g) 18 : x - 5*2 = 8

18 : x - 10 = 8

18 : x = 18

x = 1

h) 5*5 -2 : x = 24

25 - 2:x = 24

2:x = 1

x = 2