Question

Tìm số nguyên x, biết :

a) x - 7 = -5

b) 128 - 3(x + 4) = 23

c) x - [42 + (-28)] = -8

d) (7 - x) - (25 + 7) = -25

Help me!!

Answer 1

c)x-[42+(-28)]=-8

x-34=-8

x =-8+34

x =26

Answer 2

a) x - 7 = -5

\(\Leftrightarrow x=-5+7=2\)

b) 128 - 3(x + 4) = 23

\(\Leftrightarrow128-3x-12=23\)

\(\Leftrightarrow-3x=23+12-128\)

\(\Leftrightarrow-3x=-93\)

\(\Leftrightarrow x=31\)

c) x - [42 + (-28)] = -8

\(\Leftrightarrow x-42+28=-8\)

\(\Leftrightarrow x=-8+42-28=6\)

d) (7 - x) - (25 + 7) = -25

\(\Leftrightarrow7-x-25-7=-25\)

\(\Leftrightarrow-x=-25+25+7-7\)

\(\Leftrightarrow x=0\)

Answer 3

a) x-7=-5

x=-5 + 7

x= 2

b)128-3(x+4)=23

3(x+4)=128-23

3(x+4)=105

x+4=105:3

x+4=35

x=35-4

x=31

c)x-42-(-28)=-8

x-42=-8+(-28)

x-42=-36

x=-36+42

x=6

d)(7-x)-(25+7)=-25

7-x-32=-25

7-x=-25+32

7-x=7

x=7-7

x=0

Answer 4

a) x - 7 = -5

\(\Rightarrow\)x =-5 + 7

\(\Rightarrow\)x = 7 -5

\(\Rightarrow\)x = 2 ϵ Z

Vậy ...

b) 128 -3( x +4 ) =23

⇒ 3(x +4) = 128 - 23

⇒ 3(x +4) = 105

⇒ x + 4 = 105 : 3

⇒ x + 4 = 35

⇒ x =35 - 4

⇒ x = 31 ϵ Z

Vậy ...

c) x - [42 + (-28) ] = -8

⇒x - [42 -28] = -8

⇒x - 14 = -8

⇒x = (-8) +14

⇒x = 14 -8

⇒x = 6 ϵ Z

Vậy ..

d) ( 7 - x ) - ( 25 +7 ) = -25

⇒( 7 - x ) - 32 = -25

⇒ 7 - x = ( -25) +32

⇒ 7 - x = 32 - 25

⇒ 7 - x = 7

⇒ x = 7 - 7

⇒ x =0 ϵ Z

Answer 5

a)x-7=-5

x=(-5)+7

x=2

b)128-3(x+4)=23

3(x+4)=128-23

3(x+4)=105

x+4=105:3

x+4=35

x =35-4

x =31

Answer 6

d)(7-x)-(25+7)=-25

(7-x)-32=-25

7-x=-25+32

7-x=7

x=7-7

x=0