\(a,=\dfrac{3^6\cdot5^4\cdot9^4-5^{13}\cdot3^{13}\cdot5^{-9}}{3^{12}\cdot5^6+9^6\cdot5^6}=\dfrac{3^{14}\cdot5^4-5^4\cdot3^{13}}{3^{12}\cdot5^6+3^{12}\cdot5^6}\\ =\dfrac{3^{13}\cdot5^4\cdot2}{2\cdot3^{12}\cdot5^6}=\dfrac{3}{5^2}=\dfrac{3}{25}\)

\(b,=\dfrac{\left(\dfrac{2}{5}\cdot5\right)^7+\left(\dfrac{9}{4}\cdot\dfrac{16}{3}\right)^3}{2^7\cdot5^2+2^9}=\dfrac{2^7+12^3}{2^7\left(5^2+2^2\right)}=\dfrac{2^7+4^3\cdot3^3}{2^7\cdot29}=\dfrac{2^6\left(2+3^3\right)}{2^7\cdot29}=\dfrac{1}{2}\)

a) \(\dfrac{3^6\cdot3^8\cdot5^4-5^{13}\cdot3^{13}\cdot5^{-9}}{3^{12}\cdot5^6+3^{12}\cdot5^6}=\dfrac{3^{14}\cdot5^4-3^{13}\cdot5^4}{3^{12}\cdot5^6\cdot2}=\dfrac{3^{12}\cdot5^4\left(3^2-3\right)}{3^{12}\cdot5^6\cdot2}=\dfrac{3^2-3}{5^2\cdot2}=\dfrac{6}{50}=\dfrac{3}{25}\)

Sửa đề: (2/7)^7*7^7

\(A=\dfrac{\left(2\right)^7+\left(\dfrac{9}{3}:\dfrac{3}{16}\right)^3}{2^7\left(5^2+2^2\right)}\)

\(=\dfrac{\left(2\right)^7+\left(16\right)^3}{2^7\cdot29}\)

\(=\dfrac{2^7+2^7\cdot2^5}{2^7\cdot29}=\dfrac{1+2^5}{29}=\dfrac{33}{29}\)

\(A=\dfrac{\left(\dfrac{2}{5}\right)^7.5^7+\left(\dfrac{9}{4}\right)^3:\left(\dfrac{3}{16}\right)^3}{2^7.5^2+512}\\ A=\dfrac{128+1728}{153+512}\\ A=\dfrac{1856}{665}=2\dfrac{526}{665}\)

Chúc bạn học tốt!!!

\(\dfrac{\left(\dfrac{2}{5}\right)^7\cdot5^7+\left(\dfrac{9}{4}\right)^3:\left(\dfrac{3}{16}\right)^3}{2^7+5^2+512}\)

\(\dfrac{\left(\dfrac{2}{7}\right)^7.7^7+\left(\dfrac{9}{4}\right)^3:\left(\dfrac{3}{16}\right)^3}{2^7.5^2+512}\)

\(=\dfrac{\dfrac{2^7}{7^7}.7^7+\left(\dfrac{9}{4}:\dfrac{3}{16}\right)^3}{2^7.5^2+2.256}\)

\(=\dfrac{2^7+\left(\dfrac{9}{4}.\dfrac{16}{3}\right)^3}{2^7.5^2+2.2^8}=\dfrac{2^7+\left(12\right)^3}{2^7.5^2+2.2^8}\)

\(=\dfrac{2^7+\left(2^2.3\right)^3}{2^7.5^2+2^9}=\dfrac{2^7+2^6.3^3}{2^7.\left(5^2+2^2\right)}\)

\(=\dfrac{2^6\left(2+27\right)}{2^7.\left(25+4\right)}=\dfrac{29}{2.29}=\dfrac{1}{2}\)

\(A=\dfrac{\left(\dfrac{2}{5}\right)^7.5^7+\left(\dfrac{9}{4}\right)^3:\left(\dfrac{3}{16}\right)^3}{2^7.5^2+512}\)

\(A=\dfrac{128+1728}{153+512}\)

\(A=\dfrac{1856}{665}\)

\(A=2\dfrac{526}{665}\)

Bài 1:

\(\dfrac{\left(\dfrac{2}{5}\right)^7\cdot5^7+\left(\dfrac{9}{4}\right)^3:\left(\dfrac{3}{16}\right)^3}{2^7\cdot5^2+512}\)

\(=\dfrac{\left(\dfrac{2}{5}\cdot5\right)^7+\left(\dfrac{9}{4}:\dfrac{3}{16}\right)^3}{2^7\cdot5^2+512}\)

\(=\dfrac{2^7+12^3}{2^7\cdot5^2+512}\)

\(=\dfrac{1856}{3712}\)

\(=0,5\)

Bài 2:

\(\left(5x+1\right)^2=\dfrac{36}{49}\)

\(\Rightarrow5x+1=\dfrac{6}{7}\)

\(\Rightarrow5x=\dfrac{-1}{7}\)

\(\Rightarrow x=\dfrac{-1}{35}\)

bn gy gì mk k hiểu

j vay ban

không hiểu 

Bạn đổi \(\left(\frac{2}{5}\right)^7.5^7=\frac{2^7}{5^7}.5^7=2^7=128\)

\(\left(\frac{9}{4}\right)^3:\left(\frac{3}{16}\right)^3=\frac{9^3}{4^3}.\frac{16^3}{3^3}=\frac{3^3.3^3}{4^3}.\frac{4^3.4^3}{3^3}=3^3.4^3=17.64=1088\)

CỘNG 2 CÁI ĐÓ LẠI RỒI LÀM Ở TỬ SỐ LÀ RA.

BẤM ĐÚNG NẾU THẤY ĐÚNG

\(=\frac{\left(\frac{2}{5}.5\right)^7+\left(\frac{9}{4}:\frac{3}{16}\right)^3}{2^7.5^2+512}=\frac{2^7+12^3}{2^7.5^2+512}=\frac{128+1728}{3200+512}=\frac{1856}{3712}=\frac{1}{2}\)