-41/28

-7/30

47/20

-11/8

1/2

31/72

-40/39

B={x\(\in\)N|x=3^k; 1<=k<=4}

C={x\(\in\)N|x=4*a²; 1<=a<=5}

D={x\(\in\)N|x=9*a²;1<=a<=4}

E={x\(\in\)N|x=4k; 0<=x<=4}

G={x\(\in\)N|x=(-3)^k; 1<=k<=4}

nhìn lộn xộn hoa mắt quá bạn ơi

\(\frac{2^{12}.3^5-4^6.81}{\left[\left(2^2.3\right)^6+8^4.3^5\right]}=\frac{2^{12}.3^5-\left(2^2\right)^6.3^4}{2^{12}.3^6+\left(2^3\right)^4.3^5}\)

\(=\frac{2^{12}.3^5-2^{12}.3^4}{2^{12}.3^6-2^{12}.3^5}=\frac{2^{12}\left(3^5-3^4\right)}{2^{12}\left(3^6-3^5\right)}\)

\(=\frac{3^4\left(3-1\right)}{3^5\left(3-1\right)}=\frac{1}{3}\)

Thanks

Bài làm: 

\(\frac{2^{12}.3^5-4^6.81}{\left(2^2.3\right)^6+8^4.3^5}=\frac{2^{12}.3^5-2^{12}.3^4}{2^{12}.3^6+2^{12}.3^5}=\frac{2^{12}.\left(3^5-3^4\right)}{2^{12}.\left(3^6+3^5\right)}\)

                                \(=\frac{3^5-3^4}{3^6+3^5}=\frac{3^4.\left(3-1\right)}{3^5.\left(3+1\right)}=\frac{2}{3.4}=\frac{1}{6}\)

a) \(A=\left\{x\in N|0\le x\le4\right\}\)

b) \(B=\left\{x\in N|x=4k;0\le k\le4;k\in N\right\}\)

c) \(C=\left\{x\in Z|x=\left(-3\right)^k;1\le k\le4;k\in N\right\}\)

d) \(D=\left\{x\in N|x=k^2;k=3a;1\le a\le4;a\in N\right\}\)

ban tu lam di,luoi the

bai ki vay ,