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

\left(4\dfrac{4}{9} + 5\dfrac{4}{11}\right) -1\dfrac{4}{9} =(494​+5114​)−194​

A=2¹²x3⁵-4⁶x9²:(2²x3)⁶+8⁴x3⁵

  =2¹²x3⁵-2¹²x3⁴:2¹²x3⁶+2¹²x3⁵

=2¹²(3⁵-3⁴+3⁵):2¹²x3⁶=2¹²x405:(2¹²x3⁶)=1x\(\dfrac{5}{9}\)=\(\dfrac{5}{9}\).

\(\dfrac{2^{12}.3^{5}-4^{6}.9^{2}}{(2^{2}.3)^{6}}\)

\(=\dfrac{2^{12}.3^{5}-2^{12}.3^{4}}{2^{12}.3^{6}}\)

\(=\dfrac{2^{12}.3^{4}(3-1)}{2^{12}.3^{4}.3^{2}}\)

\(=\dfrac{2}{9}\)

mk ko viết lại đề

\(A=\frac{2^{12}.3^5-2^{12}.3^4}{2^{12}.3^6+2^{12}.3^5}+\frac{2^{12}.3^{10}+2^{12}.3^{10}.5}{2^{12}.3^{12}+2^{12}.3^{12}}\)

\(=\frac{2^{12}.3^4\left(3-1\right)}{2^{12}.3^5\left(3+1\right)}+\frac{2^{12}.3^{10}\left(1+5\right)}{2.\left(2^{12}.3^{12}\right)}\)

\(=\frac{2}{3.4}+\frac{2^{12}.3^{10}.6}{2.2^{12}.3^{12}}=\frac{1}{6}+\frac{1}{3}=\frac{1}{2}\)

Vậy A= \(\frac{1}{2}\)

Cảm ơn bạn nha

s bạn lại cảm ơn mik?

Nhiwf bạn nên mình làm được bài này ! Hihi