a) 81^11.3^17/27^10.9^15

=(9^2)^11.3^17/(3^3)^10.9^15

=3^44.3^17/3^30.3^30

=3^61/3^60

=3

b) A =( (2^12.3^5 - 2^12.3^4)/ (2^12.3^6 + 2^12.3^5) ) - ((5^10.7^3 - 5^10.7^4)/(5^9.7^3 + 5^9.2^3.7^3))

=(2^12.3^4(3-1))/2^12.3^5(3+1) - 5^10.7^3(1-7)/5^9.7^3(1+8)

=2/12- (-30/9)=1/6 + 10/3 = 7/2

3/6, /8,4/6

6.10+10.7+8.10+10.9 

= 10 . ( 6 + 7 + 8 + 9 )

= 10 . 30

= 300

6,10+10,7+8,10+10,9=27,8

Khó ghê

ở dòng suy ra thứ 2 nếu muốn 45= 2.5.9.2

36=2.4.9.2

thì 5^2 và 4^2 phải nhân thêm 4

\(\frac{2^{12}\cdot3^5-4^6\cdot9^2}{\left(2^3\cdot3\right)^6}-\frac{5^{10}\cdot7^3-25^5\cdot49^2}{\left(125\cdot7\right)^3+5^9\cdot14^3}\)

\(=\frac{2^{12}\cdot3^5-2^{12}\cdot3^4}{2^{18}\cdot3^6}-\frac{5^{10}\cdot7_{}^3-5^{10}\cdot7^4}{5^9\cdot7^3+5^9\cdot7^3\cdot2^3}\)

\(=\frac{2^{12}\cdot3^4\left(3-1\right)}{2^{18}\cdot3^6}+\frac{5^{10}\cdot7^3\left(7-1\right)}{5^9\cdot7^3\left(2^3+1\right)}\)

\(=\frac{2}{2^6\cdot3^2}+\frac{5\cdot6}{9}=\frac{1}{2^5\cdot9}+\frac{30}{9}=\frac{1}{32\cdot9}+\frac{960}{32\cdot9}=\frac{961}{288}\)

\(=\dfrac{2^{20}\cdot3^{12}+3^{12}\cdot2^{15}}{2^{15}\cdot3^{13}-2^{16}\cdot3^{12}}\)

\(=\dfrac{2^{15}\cdot3^{12}\left(2^5+1\right)}{2^{15}\cdot3^{12}\left(3-2\right)}\)

=33