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a) Ta có :
990 = 2.32.5.11
2610=2.32.5.29
ƯCLN(990;2610) = 2.32.5=90
\(\Rightarrow\frac{990}{2610}=\frac{990:90}{2610:90}=\frac{11}{29}\)
Tương tự với câu b)
\(a,\frac{990}{2610}=\frac{990:90}{2610:90}=\frac{11}{29}\)
\(b,\frac{374}{506}=\frac{374:2}{506:2}=\frac{187}{253}=\frac{187:11}{253:11}=\frac{17}{23}\)
\(c,\frac{3600-75}{8400-175}=\frac{3525}{8225}=\frac{3525:25}{8225:25}=\frac{141}{329}\)
\(d,\frac{9^{14}.25^5.8^7}{18^{12}.625^3.24^3}=\frac{9^{12}.9^2.25^3.25^2.8^3.8^4}{\left(9.2\right)^{12}.\left(25.25\right)^3.\left(8.3\right)^3}=\frac{9^{12}.9^2.25^3.25^2.8^3.8^3.8}{9^{12}.2^{12}.25^3.25^2.25.8^3.3^3}=\frac{9^2.8}{2^{12}.25.3^3}\) đến đây bn tự làm nốt đi!
~ mỏi ~
\(\frac{-72}{14}=\frac{-36}{7}\)
\(\frac{990}{2610}=\frac{11}{29}\)
\(\frac{374}{506}=\frac{17}{23}\)
\(\frac{3600-75}{8400-175}=\frac{3525}{8225}=\frac{3}{7}\)
hok tốt!!
\(\frac{990}{2610}=\frac{990:11}{2610:11}=\frac{11}{29}\)
\(\frac{374}{506}=\frac{374:22}{506:22}=\frac{17}{23}\)
\(\frac{3600-75}{8400-175}=\frac{3525}{8225}=\frac{3525:1175}{8225:1175}=\frac{3}{7}\)
\(\frac{9^{14}.255^5.8^7}{18^{12}.625^3.24^3}=\frac{3^{28}.5^5.3^5.17^5.2^{21}}{2^{12}.3^{24}.5^{12}.2^9.3^3}=\frac{3^{33}.5^5.17^5.2^{21}}{2^{21}.3^{27}.5^{12}}=\frac{3^6.17^5}{5^7}\)
d)
\(\dfrac{3^9.3^{20}.2^8}{3^{24}.243.2^6}\\ =\dfrac{3^{29}.2^6.2^2}{3^{24}.3^5.2^6}\\ =\dfrac{3^{29}.2^6.4}{3^{29}.2^6}\\ =4\)
e)
\(\dfrac{2^{15}.5^3.2^6.3^4}{8.2^{18}.81.5}\\ =\dfrac{2^{21}.5^3.3^4}{2^3.2^{18}3^4.5}\\ =\dfrac{2^{21}.5.5^2.3^4}{2^{21}.3^4.5}\\ =5^2\\ =25\)
f)
\(=\dfrac{24\left(315+561+124\right)}{\dfrac{\left(1+99\right).50}{2}-500}\\ =\dfrac{24.1000}{2500-500}\\ =12\)
\(a,\dfrac{-14.15}{21.\left(-10\right)}=\dfrac{-7.2.3.5}{7.3.\left(-2\right).5}=1\)
\(b,\dfrac{5.7-7.9}{7.2+6.7}=\dfrac{7\left(5-9\right)}{7\left(2+6\right)}=\dfrac{-4}{8}=-\dfrac{1}{2}\)
\(c,\dfrac{\left(-7\right).3+2.\left(-14\right)}{\left(-5\right).7-2.7}=\dfrac{-7.\left(3+4\right)}{7\left(-5-2\right)}\)
\(=\dfrac{\left(-7\right).7}{7.\left(-7\right)}=1\)
\(d,\dfrac{3^9.3^{20}.2^8}{3^{24}.243.2^6}=\dfrac{3^{29}.2^8}{3^{24}.3^5.2^6}=\dfrac{3^{29}.2^8}{3^{29}.2^6}=2^2=4\)
\(e,\dfrac{2^{15}.5^3.2^6.3^4}{8.2^{18}.81.5}=\dfrac{2^{21}.3^4.5^3}{2^{18}.2^3.3^4.5}=\dfrac{2^{21}.3^4.5^3}{2^{21}.3^4.5}=5^2=25\)
\(f,\dfrac{24.315+3.561.8+4.124.6}{1+3+5+...+97+99-500}\)
\(=\dfrac{24.315+24.561+24.124}{1+3+5+...+97+99-500}\)
\(=\dfrac{24\left(315+561+124\right)}{1+3+5+...+97+99-500}\)
\(=\dfrac{24.1000}{1+3+5+...+97+99-500}\) (1)
Đặt A = 1 + 3 + 5 + ... + 97 + 99
Số số hạng trong A là: (99 - 1) : 2 + 1 = 50 (số)
Tổng A bằng: (99 + 1) . 50 : 2 = 2500
Thay A = 2500 vào biểu thức (1), ta được:
\(\dfrac{24.1000}{2500-500}=\dfrac{24.1000}{2.1000}=12\)
a, \(\dfrac{990}{2610}=\dfrac{11}{29}\)
b) \(\dfrac{3600-75}{8400-175}=\dfrac{3}{7}\)
c) \(\dfrac{9^{14}\cdot25^5\cdot8^7}{18^{12}\cdot625^5\cdot24^3}=\dfrac{3}{25}\)
to noi that: nguoi ta chi thich giup lam bai kho thoi chu bai nay ai di hoc cung lam dc
tai sao ban phai hoi
\(\frac{3^{10}.\left(-5\right)^{21}}{\left(-5\right)^{20}.3^{12}}=\frac{3^{10}.\left(-5\right)^{20}.\left(-5\right)}{\left(-5\right)^{20}.3^{10}.3^2}=\frac{-5}{3^2}=-\frac{5}{9}\)
dễ lắm mà
ừa, nhưng mik còn những câu sau khó hơn nhưng mỏi tay quá nên tí gửi tiếp!