Question

Tìm số tự nhiên x, biết :

a) (2600 + 6400) - 3 . =1200;

b) [(6 . x - 72) :2 - 84] . 28 + 5628

GIÚP!!!!!!!!!

Answer 1

a) (2600 + 6400) - 3 . x = 1200

           9000 - 3.x         = 1200

                  3x             = 9000-1200

                  3x             =  7800

                    x             = 7800:3

                    x             = 2600

b) câu này ko có tổng hả Công chúa nhí nhảnh? check lại giùm Nhi nha!

Answer 2

a)  \(\left(2600+6400\right)-3x=1200\)

\(9000-3x=1200\)

\(3x=9000-1200\)

\(3x=7800\)

\(x=\frac{7800}{3}\)

\(x=2600\)

vậy \(x=2600\)

b) \(\left[\left(6x-72\right):2-84\right].28+5628=0\)

\(\left[\frac{6x}{2}-\frac{72}{2}-84\right].28+5628=0\)

\(\left[3x-36-84\right].28=-5628\)

\(3x-120=\frac{-5628}{28}\)

\(3x-120=-201\)

\(3x=-201+120\)

\(3x=-81\)

\(x=-27\)

vậy \(x=-27\)

Answer 3

Ban kia lam dung roi do 

k tui nha

thanks

Answer 4

Bạn kia làm đúng ròi

k mik nha!^_^

Thanks

Answer 5

\(\text{a) }\left(2600+6400\right)-3x=1200\)

\(\Leftrightarrow9000-3x=1200\)

\(\Leftrightarrow9000-1200=3x\)

\(\Leftrightarrow7800=3x\)

\(\Leftrightarrow x=\frac{7800}{3}\)

\(\Leftrightarrow x=2600\)

\(\text{Vậy }x=2600\)

\(\text{b) }\left[\left(6x-72\right)\div2-84\right].28=5628\)

\(\Leftrightarrow\left(6x-72\right)\div2-84=\frac{5628}{28}\)

\(\Leftrightarrow\left(6x-72\right)\div2-84=201\)

\(\Leftrightarrow\frac{6x-72}{2}=201+84\)

\(\Leftrightarrow\frac{6x-72}{2}=285\)

\(\Leftrightarrow6x-72=285.2\)

\(\Leftrightarrow6x-72=570\)

\(\Leftrightarrow6x=570+72\)

\(\Leftrightarrow6x=642\)

\(\Leftrightarrow x=\frac{642}{6}\)

\(\Leftrightarrow x=107\)

\(\text{Vậy }x=107\)