\(\left(X-7\right)^{x+1}-\left(x-7\right)^{x+11}=0\) \(\)

 tìm x:   

\(a,5^x.\left(5^2\right)^3=625\)

\(b,\left(\dfrac{12}{15}\right)^x=\left(\dfrac{5}{4}\right)^{-2}-\left(\dfrac{-3}{5}\right)^4\)

\(c,\left(\dfrac{-3}{4}\right)^{3x-1}=\dfrac{256}{81}\)

\(d,172x^2-7^9:98^3=2^{-3}\)