Ta có: \(B=\dfrac{30\cdot4^7\cdot3^{29}-5\cdot14^5\cdot2^{12}}{54\cdot6^{14}\cdot9^7-12\cdot8^5\cdot7^5}\)

\(=\dfrac{3^{30}\cdot2^{15}\cdot5-5\cdot2^{17}\cdot7^5}{3^{31}\cdot2^{15}-2^{17}\cdot3\cdot7^5}\)

\(=\dfrac{2^{15}\cdot5\left(3^{30}-2^2\cdot7^5\right)}{3\cdot2^{15}\left(3^{30}-2^2\cdot7^5\right)}\)

\(=\dfrac{5}{3}\)

Mik ko chắc lắm đâu nha(/Mik làm tắc nên mất phấn tắc ra TSNT)

B=5/3

B=\(\frac{5}{3}\)NHa bạn

ai cho mik ik 

B=\(\frac{5}{3}\)nhớ tích

\(B=\frac{5.2^{15}.3^{30}-5.7^5.2^5.2^{12}}{5^4.2^{14}.3^{14}.3^7.3^7-2^2.3.2^{15}.7^5}\)

=> \(B=\frac{5.2^{15}.3^{30}-5.7^5.2^{17}}{5^4.2^{14}.3^{28}-2^{17}.3.7}\)

=> \(B=\frac{5.2.3^{30}-5.7^5.2^3}{5^4.3^{28}-2^3.3.7}=0,144\)

= \(\dfrac{5}{2}\)

bạn THAM KHẢO thôi nhé!

Kq = 5/2 nha bạn câu này đã có người hỏi rồi bạn tự tham khảo nhé 

\(...=\dfrac{2.3.5.2^{14}.3^{29}-5.2^5.7^5.2^{12}}{3^2.2.3.2^{14}.3^{14}.3^4-3.2^2.2^{15}.7^5}\)

\(=\dfrac{2^{15}.3^{30}.5-2^{17}.5.7^5}{2^{15}.3^{21}-2^{17}.3.7^5}\)

\(=\dfrac{2^{15}.5\left(3^{30}-2^2.7^5\right)}{2^{15}.3.\left(3^{20}-2^2.7^5\right)}\)

\(=\dfrac{5\left(3^{30}-2^2.7^5\right)}{3.\left(3^{20}-2^2.7^5\right)}\)

\(=\dfrac{3^{30}\cdot2^{15}\cdot5-5\cdot2^{17}\cdot7^5}{2^{14}\cdot3^{14}\cdot3^3\cdot2\cdot3^{14}-2^{15}\cdot7^5\cdot2^2\cdot3}\)

\(=\dfrac{2^{15}\cdot5\left(3^{30}-2^2\cdot7^5\right)}{2^{15}\cdot3^{31}-2^{17}\cdot7^5\cdot3}\)

\(=\dfrac{2^{15}\cdot5\left(3^{30}-2^2\cdot7^5\right)}{2^{15}\cdot3\left(3^{30}-2^2\cdot7^5\right)}=\dfrac{5}{3}\)