Question

Bài 1 : Rút gọn :

a) (0,25)³. 32

b) \(\dfrac{72^3.54^2}{108^4}\)

c) \(\dfrac{81^{11}.3^{17}}{27^{10}.9^{15}}\)

Bài 2: cho A =2.2².2³...2¹⁰.5².5⁴...5¹⁴

Hỏi A có tận cùng là bao nhiêu chữ số 0 ?

Answer 1

a, (0,25)³.32
= 0,5
b, \(\dfrac{72^3.54^2}{108^4}=\dfrac{\left(2^3.3^2\right)^3.\left(2.3^3\right)^2}{\left(2^2.3^3\right)^4}\)\(=\dfrac{2^9.3^6.2^2.3^6}{2^8.3^{12}}\)
\(=\dfrac{2^{11}.3^{12}}{2^8.3^{12}}=2^3\)
c, \(\dfrac{81^{11}.3^{17}}{27^{10}.9^{15}}=\dfrac{\left(3^4\right)^{11}.3^{17}}{\left(3^3\right)^{10}.\left(3^2\right)^{15}}=\dfrac{3^{44}.3^{17}}{3^{30}.3^{30}}\)\(=\dfrac{3^{61}}{3^{60}}=3\)
@Lớp 6B Đoàn Kết