`16x^2 = (x+1)^2`

`(4x)^2 - (x+1)^2 =0`

`(4x-x-1)(4x+x+1)=0``

`(3x-1)(5x+1)=0`

`=>[(3x=1),(5x=-1):}`

`=> [(x=1/3),(x=-1/5):}`

Vậy `x in {1/3;-1/5}`

`F = 4/9 * 13/17 +2/17 * 4/9 + 2/9 * 4/17`

`F = 4/9 * 13/17 +2/17 * 4/9 + (2.4)/(9.17)`

`F = 4/9 ( 13/17 + 2/17 + 2/17)`

`F = 4/9 *17/17 =4/9*1 = 4/9`

`280 : (7+3x) = 4`

`<=> 7+3x = 280 : 4 =70`

`<=> 3x = 70-7 = 63`

`<=> x = 63/3 =21`

`y = 7/8 - 1/7 `

`y = 49/56 - 8/56 = 41/56`

`3^2 .2^5 .(2/3)^2`

`= 9 . 32 . 4/9`

`= (9.4)/9 .32`

`= 1/4 .32 = 8 =2^3`

`(1/3)^2 . 1/3 .9 `

`= 1/9 . 1/3 .9`

`=  1.1/3 ` \(=\left(\dfrac{1}{\sqrt{3}}\right)^2\) 

`9.3^3 .1/81 .3^2 `

`= 9. 3^3/3^4 .3^2`

`= 9.1/3 .9 = 9/3 .3 = 3.3 =9 =3^2`

`4.2^5 :(2^3 .1/16)`

`= 4. 32 : (8/16)`

`= 4.32:1/2 = 4.32.2 = 256 = 2^8`

Số tiền mỗi kg thịt là 

`280000:2 = 140000(đồng)`

Mẹ mua 5kg thịt hết 

`5xx  140000 = 700000(đồng)`

`30:x=7,5`

`=> x = 30:7,5`

`=> x= 4`

Vậy `x=4`