Question

[Hotaru]

tìm x:

4 ( x + 3 ) - 3 ( x - 3 ) =21

Answer 1

[Hàn Ma Kết]

4 . (x + 3) - 3 . (x - 3) = 21

4.x + 4.3 - 3.x  - 3.3 = 21

4x + 12 - 3x - 9 = 21

4x - 3x + 12 - 9 = 21

x + 12 - 9 = 21

x + 3 = 21

x = 21 : 3

x = 7.

Vậy x = 7.

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Answer 2

[Nguyễn Tiến Dũng]

\(4\left(x+3\right)-3\left(x-3\right)=21\)

\(\Leftrightarrow4x+12-3x+9=21\)

\(\Leftrightarrow x=21-12-9\)

\(\Leftrightarrow x=0\)

Vậy.....