Question

tìm số tự nhiên x , biết:

a) (9x - 2³) : 5 = 2               ;                    b) [3⁴ - ( 8² + 14) : 13]x = 5³ + 10²

Answer 1

`a) (9x-2^3) :5 =2`

` (9x-2^3)  = 2*5=10`

`9x -8=10`

`9x = 18`

`x =18/9 =2`

`b)[3^4 -(8^2+14):13]x =5^3 +10^2`

`[ 81 - (64 +14) :13]x = 125 + 100`

`[81 - 78 :13] x = 225`

` (81-6)x =225`

`75x =225`

`x =225/75=3`

Answer 2

a) (9x - 2³) : 5 = 2

9x - 2³ = 2 . 5

9x - 8 = 10

9x = 10 + 8

9x = 18

x = 18 : 2

x = 9

b) [3⁴ - (8² + 14) : 14) ]x = 5³ + 10²

[81 - (64 + 14) : 13]x = 125 + 100

(81 - 78 : 13)x = 225

(81 - 6)x = 225

75x = 225

x = 225 : 75

x = 3