Question

Tìm x biết:

a) 5.(x-7) = 0

b) 34.(2.x - 6 ) = 0

c) 25 + (15-x) = 30

d) 43 -(24-x) = 20

e) 2. (x - 5) -17 =25

f) 24 + 3.(5 - x) = 27

g) 15 : x – 2 = 3

h) (32 – x : 5): 13 = 2

g) (6 – 2x)(x – 8) =0

Mg bt câu nào thỳ giúp mk câu đó nhé

Answer 1

a ) \(5.\left(x-7\right)=0\)

\(\Leftrightarrow x-7=5.0\)

\(\Leftrightarrow x-7=0\)

\(\Leftrightarrow x=7\)

b ) \(34.\left(2.x-6\right)=0\)

\(\Leftrightarrow2.x-6=34.0\)

\(\Leftrightarrow2.x-6=0\)

\(\Leftrightarrow2.x=0+6\)

\(\Leftrightarrow2.x=6\)

\(\Leftrightarrow x=6\div2\)

\(\Leftrightarrow x=3\)

c ) \(25+\left(15-x\right)=30\)

\(\Leftrightarrow25+\left(15-x\right)=-\left(x-40\right)\)

\(\Leftrightarrow-\left(x-40\right)=2.3.5\)

\(\Leftrightarrow40-x=30\)

\(\Leftrightarrow-x=-10\)

\(\Leftrightarrow x=10\)

d ) \(43-\left(24-x\right)=20\)

\(\Leftrightarrow24-x=43-20\)

\(\Leftrightarrow24-x=23\)

\(\Leftrightarrow x=24-23\)

\(\Leftrightarrow x=1\)

e ) \(2.\left(x-5\right)-17=25\)

\(\Leftrightarrow2.\left(x-5\right)=25+17\)

\(\Leftrightarrow2.\left(x-5\right)=42\)

\(\Leftrightarrow x-5=42\div2\)

\(\Leftrightarrow x-5=21\)

\(\Leftrightarrow x=21+5\)

\(\Leftrightarrow x=26\)

f ) \(24+3.\left(5-x\right)=27\)

\(\Leftrightarrow3.\left(5-x\right)=27-24\)'

\(\Leftrightarrow3.\left(5-x\right)=3\)

\(\Leftrightarrow5-x=3\div3\)

\(\Leftrightarrow5-x=1\)

\(\Leftrightarrow x=5-1\)

\(\Leftrightarrow x=4\)

g ) \(15\div x-2=3\)

\(\Leftrightarrow15\div x=3+2\)

\(\Leftrightarrow15\div x=5\)

\(\Leftrightarrow x=15\div5\)

\(\Leftrightarrow x=3\)

h ) \(\left(32-x\div5\right)\div13=2\)

\(\Leftrightarrow32-x\div5=2\times13\)

\(\Leftrightarrow32-x\div5=26\)

\(\Leftrightarrow x\div5=32-26\)

\(\Leftrightarrow x\div5=6\)

\(\Leftrightarrow x=5.6\)

\(\Leftrightarrow x=30\)

g ) \(\left(6-2x\right)\left(x-8\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}6-2x=0\\x-8=0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=3\\x=8\end{matrix}\right.\)

Vậy \(x\in\left\{3;8\right\}\)

Mình làm hết nhaa !!

Answer 2

a)5.(x-7)=0

x-7=0:5

x-7=0

x=0+7

x=7

Vậy x=7

b)34.(2x-6)=0

2x-6 =0:34

2x-6 =0

2x=0+6

2x=6

x=6:2

x=3

Vậy x= 3

c)25+(15-x)=30

15-x=30-25

15-x=5

x=15-5

x=10

Vậy x=10

d)43-(24-x)=20

24-x =43-20

24-x=23

x=24-23

x=1

vậy x=1

e)2(x-5)-17=25

2(x-5)=25+17

2(x-5)=42

x-5=42:2

x-5=21

x=21+5

x=26

Vậy x=26

f)24+3(5-x)=27

3(5-x)=27-24

3(5-x)=3

5-x =3:3

5-x=1

x=5-1

x=4

Vậy x=4

g)15:x-2=3

15:x=3+2

15:x=5

x=15:5

x=3

Vậy x=3

h)( 32-x:5):13=2

32-x:5 =2.13

32-x :5=26

x:5= 32-26

x:5=6

x=6.5

x=30

Vậy x=30

k)(6-2x)(x-8)=0

➩6-2x=0 hoặc x-8=0

2x=6-0 x=0+8

2x=6 x=8

x=6:2

x=3

Vậy x=3 hoặc x=8