các bn ko cần lm bài 6 đâu ạ. mik chụp bị thừa bài 6 ắ
Bài 6:
a) \(\left(-\dfrac{6}{5}\right)^4\cdot\left(\dfrac{6}{5}\right)^7\)
\(=\left(\dfrac{6}{5}\right)^4\cdot\left(\dfrac{6}{5}\right)^7\)
\(=\left(\dfrac{6}{5}\right)^{4+7}\)
\(=\left(\dfrac{6}{5}\right)^{11}\)
b) \(\left(-\dfrac{7}{13}\right)^7\cdot\left(-\dfrac{7}{13}\right)^9\)
\(=\left(-\dfrac{7}{13}\right)^{7+9}\)
\(=\left(-\dfrac{7}{13}\right)^{16}=\left(\dfrac{7}{13}\right)^{16}\)
c) \(\left(\dfrac{4}{9}\right)^{11}\cdot\left(-\dfrac{4}{9}\right)^8\)
\(=\left(\dfrac{4}{9}\right)^{11}\cdot\left(\dfrac{4}{9}\right)^8\)
\(=\left(\dfrac{4}{9}\right)^{11+8}\)
\(=\left(\dfrac{4}{9}\right)^{19}=\left[\left(\dfrac{2}{3}\right)^2\right]^{19}=\left(\dfrac{2}{3}\right)^{38}\)
Bài 7:
a) \(\left(-\dfrac{3}{5}\right)^7:\left(-\dfrac{3}{5}\right)\)
\(=\left(-\dfrac{3}{5}\right)^{7-1}\)
\(=\left(-\dfrac{3}{7}\right)^6\)
b) \(\left(\dfrac{6}{13}\right)^{11}:\left(\dfrac{6}{13}\right)^9\)
\(=\left(\dfrac{6}{13}\right)^{11-9}\)
\(=\left(\dfrac{6}{13}\right)^2\)
c) \(\left(-\dfrac{1}{5}\right)^{10}:\left(\dfrac{1}{5}\right)^7\)
\(=\left(\dfrac{1}{5}\right)^{10}:\left(\dfrac{1}{5}\right)^7\)
\(=\left(\dfrac{1}{5}\right)^{10-7}\)
\(=\left(\dfrac{1}{5}\right)^3\)
