Tìm GTNN của biểu thức: A = \(x\left(x+2\right)+2\left(x-\frac{2}{3}\right)\)

a/\(\frac{4^5.9^4-2.6^9}{2^{10}.3^8+6^8.20}=\frac{\left(2^2\right)^5.\left(3^2\right)^4-2.\left(2.3\right)^9}{2^{10}.3^8+\left(2.3\right)^8.2^2.5}\)

= \(\frac{2^{10}.3^8-2.2^9.3^9}{2^{10}.3^8+2^8.3^8.2^2.5}=\frac{2^{10}.3^8-2^{10}.3^9}{2^{10}.3^8+2^{10}.3^8.5}=\frac{2^{10}.3^8.\left(1-3\right)}{2^{10}.3^8\left(1+5\right)}=\frac{1-3}{1+5}=\frac{-2}{6}=-3\)

theo bài ra ta có:

\(\frac{x}{113}=\frac{113}{x}\Rightarrow x^2=113^2\)

=> x = 113 hoặc -113

mà x<0 => x = -113

vậy x = -113