Tìm x :
a, 7 – 3 x ( x + 1 ) =1 b, 12 : ( x + 5 ) +4 = 6
c, 5 x ( 2 nhân x – 3 ) + 1 = 16 d, 7 + 4 : ( 5 – 2 nhân x ) = 11
Tìm x : a, 7 – 3 x ( x + 1 ) =1 b, 12 : ( x + 5 ) +4 = 6 c, 5 x ( 2 nhân x – 3 ) + 1 = 16 d, 7 + 4 : (
By Melanie
`a, 7 – 3 × ( x + 1 ) =1`
`3×(x+1)=7-1`
`3×(x+1)=6`
`x+1=6:3`
`x+1=2`
`x=2-1`
`x=1`
$\text{Vậy x=1}$
`b, 12 : ( x + 5 ) +4 = 6`
`12:(x+5)=6-4`
`12:(x+5)=2`
`x+5=12:2`
`x+5=6`
`x=6-5`
`x=1`
$\text{Vậy x=1}$
`c, 5 × ( 2 × x – 3 ) + 1 = 16`
`5×(2x-3)=16-1`
`5×(2x-3)=15`
`2x-3=15:5`
`2x-3=3`
`2x=3+3`
`2x=6`
`x=6:2`
`x=3`
$\text{Vậy x=3}$
`d, 7 + 4 : ( 5 – 2 × x ) = 11`
`4:(5-2x)=11-7`
`4:(5-2x)=4`
`5-2x=4:4`
`5-2x=1`
`2x=5-1`
`2x=4`
`x=4:2`
`x=2`
$\text{Vậy x=2}$
a, 7 – 3 . ( x + 1 ) =1
3 . ( x + 1 ) = 7 – 1
3 . ( x + 1 ) = 6
x + 1 = 6 : 3
x + 1 = 2
x = 3
b, 12 : ( x + 5 ) +4 = 6
12 : ( x + 5 ) = 6 – 4
12 : ( x + 5 ) = 2
x + 5 = 12 : 2
x + 5 = 6
x = 1
c, 5 x ( 2 . x – 3 ) + 1 = 16
5 x ( 2 . x – 3 ) = 16 – 1
5 x ( 2 . x – 3 ) = 15
2 . x – 3 = 15 : 5
2 . x – 3 = 3
2 . x = 3 + 3
2 . x = 6
x = 3
d, 7 + 4 : ( 5 – 2 . x ) = 11
4 : ( 5 – 2 . x ) = 11 – 7
4 : ( 5 – 2 . x ) = 4
5 – 2 . x = 4 : 4
5 – 2 . x = 1
2 .x = 5 – 1
2 .x = 4
x = 4 : 2
x = 2