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\(\frac{9.5^{20}.27^9-3.9^{15}.25^9}{7.3^{29}.125^6-3.3^9.15^{19}}\)
\(=\frac{3^2.5^{20}.3^{27}-3.3^{30}.5^{18}}{7.3^{29}.5^{18}-3^{10}.3^{19}.5^{19}}\)
\(=\frac{3^{29}.5^{18}.5^2-3^2.3^{29}.5^{18}}{7.3^{29}.5^{18}-3^{29}.5^{18}.5}\)
\(=\frac{3^{29}.5^{18}.\left(5^2-3^2\right)}{3^{29}.5^{18}.\left(7-5\right)}\)
\(=\frac{25-9}{2}\)
\(=\frac{16}{2}=8\)
\(2.x=\frac{1+2+3+...+9}{1-2+3-4+5-6+7-8+9}+\frac{25.150-60.5+20.75}{1+2+3+...+99}\)
\(2.x=\frac{\left(9+1\right).9:2}{\left(1-2\right)+\left(3-4\right)+\left(5-6\right)+\left(7-8\right)+9}+\frac{2.3.5^2.\left(5^2-2+2.5\right)}{\left(1+99\right).99:2}\)
\(2.x=\frac{45}{\left(-1\right)+\left(-1\right)+\left(-1\right)+\left(-1\right)+9}+\frac{2.3.5^2.33}{100.99.\frac{1}{2}}\)
\(2x=\frac{45}{5}+\frac{50.99}{50.2.99.\frac{1}{2}}=9+\frac{1}{2.\frac{1}{2}}=9+1=10\)
=> 2x = 10
x = 5
\(\left(15.3^{42}-9^{20}\right):27^3\)
\(=\left(5.3.3^{42}-3^{40}\right):3^9\)
\(=\left(5.3^{43}-3^{40}\right):3^9\)
\(=3^{40}\left(5.3^3-1\right):3^9\)
\(=3^{31}\left(5.3^3-1\right)\)
\(=134.3^{31}\)
\(\left(15.3^{42}-9^{20}\right):27^3=15.3^{42}:27^3-9^{20}:27^3\\ \\ =15.3^{42}:\left(3^3\right)^3-9^{20}:9^3:3^3=15.3^{33}-\left(3^2\right)^{20}:\left(3^2\right)^3:3^3\)
\(=15.3^{33}-3^{40}:3^6:3^3=15.3^{33}-3^{31}\\ \\ =15.3^2.3^{31}-3^{31}=135.3^{31}-3^{31}\\ \\ =3^{31}.\left(135-1\right)=3^{31}.134\)
\(\frac{1}{2}+\frac{1}{5}+\frac{2}{9}\)
=\(\frac{45}{90}+\frac{18}{90}+\frac{20}{90}\)
=\(\frac{83}{90}\)
a, -(-29 – 7) + (-44 + 19)
\(=36-25\)
\(=11\)
b, (34 – 54 – 9) – 45 – (-3)
\(=-29-45+3\)
\(=-71\)
c, -(-27 – 77 – 2) + 78
\(=106+78\)
\(=184\)
d, 25 + (-81 – 6 – 20)
\(=25-107\)
\(=-82\)
chúc bạn học tốt
\(2^{x+1}=4=2^2\Rightarrow x+1=2\Rightarrow x=1\)
\(2^{x-1}=4=2^2\Rightarrow x-1=2\Rightarrow x=3\)
\(2^x.4=128=4.32=4.2^5\Rightarrow x=5\)
\(3^{x-2}.9=81=9.9=9.3^2\Rightarrow x-2=2\Rightarrow x=4\)
\(\frac{3^{x+1}}{9}=3\Rightarrow3^{x+1}=27=3^3\Rightarrow x=2\)
\(41-2^x=9\Rightarrow2^x=41-9=32=2^5\Rightarrow x=5\)
Quá 20h rồi không biết được ko
Ta có : 10 phút = 1/6 giờ
30 phút = 1/2 giờ
45 phút = 3/4 giờ
20 phút = 1/3 giờ
40 phút = 2/3 giờ
10 phút = \(\frac{10}{60}=\frac{1}{6}\)giờ
30 phút = \(\frac{30}{60}=\frac{1}{2}\)giờ
12 phút = \(\frac{12}{60}=\frac{1}{5}\)giờ
45 phút = \(\frac{45}{60}=\frac{3}{4}\)giờ
20 phút = \(\frac{20}{60}=\frac{1}{3}\)giờ
40 phút = \(\frac{40}{60}=\frac{2}{3}\)giờ
\(\frac{27^{20}+9^{20}}{9^{25}+81^5}=\frac{3^{60}+3^{60}}{3^{50}+3^{20}}=\frac{3^{20}\left(3^{40}+3^{40}\right)}{3^{20}\left(3^{30}+1\right)}=\frac{3^{40}.2}{3^{30}+1}\)