vậy mà cũng đăng sao!!!!!!

3^x + 3^x+3 = 3^x * (1 + 3³) = 3^x * 28 = 756

suy ra 3^x = 756 : 28 = 27 = 3³

suy ra x = 3

k cho mk để mk biết bn còn tỉnh táo

\(Đây\)\(mới\)\(là\)\(câu\)\(trả\)\(lời\)\(đúng\)

\(ta\)\(có\)\(16\left(x^2-y^2-z^2\right)=16\left(x^2-y^2\right)-16z^2=8\left(x-y\right)2\left(x-y\right)-\left(4z\right)^2=\left(8x-8y\right)\left(2x+2y\right)-\left(4z\right)^2=\left(5x-3y+3x-5y\right)\left(5x-3y-3x+5y\right)-\left(4z\right)^2\)

\(=\left(5x-3y\right)^2-\left(3x-5y\right)^2-16z^2\)

\(\Leftrightarrow\left(5x-3y\right)^2-\left(4z\right)^2=\left(3x-5y\right)^2\)

\(\Leftrightarrow\left(5x-3y-4z\right)\left(5x-3y+4z\right)=\left(3x-5y\right)^2\)

\(\frac{8^{15}\times3^{16}}{4^{22}\times9^8}\)
\(=\frac{2^{45}\times3^{16}}{2^{44}\times3^{16}}\)
\(=2\)