a. \(25.5^3.\frac{1}{625}.5^2=5^2.5^3.\frac{1}{5^4}.5^2=\frac{5^7}{5^4}=5^3\)

b. \(4.32:\left(2^3.\frac{1}{16}\right)=2^2.2^5:2^3:\frac{1}{2^4}=\frac{2^4}{2^4}=1\)

c. \(5^2.3^5.\left(\frac{3}{5}\right)^2=5^2.3^5.3^2.\frac{1}{5^2}==\frac{5^2}{5^2}.3^7=3^7\)

d. \(\left(\frac{1}{7}\right)^2.\frac{1}{7}.49^2=\frac{1}{7^3}.7^4=\frac{7^4}{7^3}=7\)

1.
a) \(3^4\times3^5\times3^6=3^{4+5+6}=3^{15}\)

b) \(5^2\times5^4\times5^5\times25=5^2\times5^4\times5^5\times5^2=5^{2+4+5+2}=5^{13}\)

c) \(10^8\div10^3=10^{8-3}=10^5\)

d) \(a^7\div a^2=a^{7-2}=a^5\)

2.

\(987=900+80+7\\ =9\times100+8\times10+7\\ =9\times10^2+8\times10^1+7\times10^0\)

\(2021=2000+20+1\\ =2\times1000+2\times10+1\times1\\ =2\times10^3+2\times10^1+1\times10^0\)

\(abcde=a\times10000+b\times1000+c\times100+d\times10+e\times1\\ =a\times10^4+b\times10^3+c\times10^2+d\times10^1+e\times10^0\)

còn bài 2

a) \(\left(\frac{1}{7}\right)^2.\frac{1}{7}.49^2=\left(\frac{1}{7}\right)^3.\left(7^2\right)^2=\left(\frac{1}{7}\right)^3.7^4=\frac{1^3}{7^3}.7^4=7^1\)

b) \(5^2.3^5.\left(\frac{3}{5}\right)^2=5^2.3^5.\frac{3^2}{5^2}=\frac{5^2.3^5.3^2}{5^2}=3^7\)

a: \(\left(\dfrac{1}{5}\right)\cdot\left(\dfrac{1}{5}\right)^{15}=\left(\dfrac{1}{5}\right)^{1+15}=\left(\dfrac{1}{5}\right)^{16}\)

b: \(\left(-10,2\right)^{10}:\left(-10,2\right)^3=\left(-10,2\right)^{10-3}=\left(-10,2\right)^7\)

c: \(\left[\left(-\dfrac{7}{9}\right)^7\right]^8=\left(-\dfrac{7}{9}\right)^{7\cdot8}=\left(-\dfrac{7}{9}\right)^{56}\)

\(\begin{array}{l}a){15^8}{.2^4} = {15^{2.4}}{.2^4} = {({15^2})^4}{.2^4}\\ = {225^4}{.2^4} = {(225.2)^4} = {450^4}\\b){27^5}:{32^3} = {({3^3})^5}:{({2^5})^3}\\ = {3^{3.5}}:{2^{5.3}} = {3^{15}}:{2^{15}} = {\left( {\frac{3}{2}} \right)^{15}}\end{array}\)

a) \(15^8\cdot2^4=3^8\cdot5^8\cdot2^4=9^4\cdot25^4\cdot2^4=\left(9\cdot25\cdot2\right)^4=450^4\) 

b) \(27^5:32^3=\left(3^3\right)^5:\left(2^5\right)^3=3^{15}:2^{15}=\left(\dfrac{3}{2}\right)^{15}\)

bài 2: n=6