Câu 2.
\(a)\)\(\left(\dfrac{1}{5}\right)\cdot\left(\dfrac{1}{5}\right)^{15}=\left(\dfrac{1}{5}\right)^{1+15}=\left(\dfrac{1}{5}\right)^{16}\)
\(b)\)\(\left(-10,2\right)^{10}:\left(-10,2\right)^3=\left(-10,2\right)^{10-3}=\left(-10,2\right)^7\)
\(c)\) \(\left[\left(-\dfrac{7}{9}\right)^7\right]^8=\left(-\dfrac{7}{9}\right)^{7\cdot8}=\left(-\dfrac{7}{9}\right)^{56}\)
Câu 3.
\(a)\)\(\sqrt{20}=4,47213595...\approx4,47\)
\(b)\)\(-\sqrt{134}=-11,57583...\approx-11,58\)
\(c)\) \(\sqrt{2021}=44,9555335...\approx44,96\)
#Ayumu
3:
a: \(\sqrt{20}\simeq4,47\)
b: \(-\sqrt{134}\) không phải căn bậc hai số học nha bạn
c: \(\sqrt{2021}\simeq44,96\)
