Đáp án:
Giải thích các bước giải:
a/
$\dfrac{20^5.5^7}{100^5}$
$=\dfrac{20^5.5^5.5^2}{100^5}$
$=\dfrac{100^5.5^2}{100^5}$
$=5^2$
$=25$
b/ $\dfrac{6^3+3.6^2+3^3}{-13}$
$=\dfrac{3^3.2^3+3.3^2.2^2+3^3}{-13}$
$=\dfrac{3^3(2^3+2^2+1}{-13}$
$=\dfrac{3^3.13}{-13}$
$=-3^3$
$=-27$
c/ Tử: $4^6.9^5+6^9.120$
$=(2^2)^6.(3^2)^5+2^9.3^9.2^3.3.5$
$=2^{12}.3^{10}+2^{12}.3^{10}.5$
$=2^{12}.3^{10}.(1+5)$
$=2^{12}.3^{10}.2.3$
$=2^{13}.3^{11}$
Mẫu: $8^4.3^{12}-6^{11}$
$=(2^3)^4.3^{12}-2^{11}.3^{11}$
$=2^{12}.3^{12}-2^{11}.3^{11}$
$=2^{11}.3^{11}.(2.3-1)$
$=2^{11}.3^{11}.5$
⇒ $\dfrac{4^6.9^5+6^9.120}{8^4.3^{12}-6^{11}}$
$=\dfrac{2^{13}.3^{11}}{2^{11}.3^{11}.5}$
$=\dfrac{2^2}{5}$
$=\dfrac{4}{5}$
chúc bạn học tốt !!!
