tính
a) A = \(\dfrac{6^3+3.6^2+3^3}{-13}\)
b) B =\(\dfrac{2.8^4.27^2+4.6^9}{2^3.6^7+2^7.40.9^4}\)
c) C=\(\dfrac{5.4^{15}.9^9-4.3^{20}.8^9}{5.2^{16}.6^{19}-7.2^{29}.27^6}\)
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a)= 2021.2021-2020.(2021+1)
= 2021.(2020+1)-2020.(2021+1)
= (2021.2020)+2021-(2020.2021)-2020
= 1
b) B= (1+2-3-4)+(5+6-7-8)+(9+10-11-12)...........+(2017+2018-2019-2020)+2021
B= -4+(-4)+....................(-4)+2021
B= -4x505+2021
B= -2020 + 2021
B = 1
a: \(A=21\cdot100-11\cdot100+90\cdot100+100\cdot125\cdot16\)
\(=100\left(21-11+90\right)+100\cdot2000\)
\(=100\left(10+90+2000\right)=2100\cdot100=210000\)
b: \(=\dfrac{5\cdot2^{30}\cdot3^{18}-2^{29}\cdot3^{20}}{5\cdot2^{28}\cdot3^{19}-7\cdot2^{29}\cdot3^{18}}\)
\(=\dfrac{2^{29}\cdot3^{18}\left(5\cdot2-3^2\right)}{2^{28}\cdot3^{18}\left(5\cdot3-7\cdot2\right)}=2\)
\(=\dfrac{5\cdot2^{30}\cdot3^{18}-2^{29}\cdot3^{20}}{5\cdot2^{29}\cdot3^{19}-7\cdot2^{29}\cdot3^{18}}=\dfrac{2^{29}\cdot3^{18}\left(5\cdot2-3^2\right)}{2^{29}\cdot3^{18}\left(5\cdot3-7\right)}=\dfrac{10-9}{15-7}=\dfrac{1}{8}\)
\(\dfrac{5.4^{15}.9^9-4.3^{20}.8^9}{5.2^9.6^{19}-7.2^{29}.27^6}\) (sửa \(-9^9\rightarrow.9^9\))
\(=\dfrac{5.2^{30}.3^{18}-2^2.3^{20}.2^{27}}{5.2^9.2^{19}.3^{19}-7.2^{29}.3^{18}}\)
\(=\dfrac{5.2^{30}.3^{18}-2^{29}.3^{20}}{5.2^{28}.3^{19}-7.2^{29}.3^{18}}\)
\(=\dfrac{2^{29}.3^{18}\left(15-9\right)}{2^{28}.3^{18}\left(15-14\right)}\)
\(=2.6=12\)
\(\dfrac{5.4^{15}.9^9+4.3^{20}.8^9}{5.2^{10}.6^{19}-7.2^{29}.27^6}=\dfrac{5.2^{30}.3^{18}+2^2.3^{20}.2^{27}}{5.2^{10}.2^{19}.3^{19}-7.2^{29}.3^{18}}\)
=\(\dfrac{5.2^{30}.3^{18}+2^{29}.3^{20}}{5.2^{29}.3^{19}-7.2^{29}.3^{18}}=\dfrac{2^{29}.3^{18}\left(5.2+3^2\right)}{2^{29}.3^{18}\left(5.3-7\right)}\)
=\(\dfrac{10+9}{15-7}=\dfrac{19}{8}\)
Bạn cho mình hỏi là 5.4 vs mấy cái tương tự là 5 nhân 4 hay 5,4 vậy?
\(A=\dfrac{5.4^{15}.9^9-4.3^{20}.8^9}{7.2^{29}.27^6-5.2^9.6^{19}}\)
\(A=\dfrac{5.2^{30}.3^{18}-2^2.3^{20}.2^{27}}{7.2^{29}.3^{18}-5.2^9.2^{19}.3^{19}}\)
\(A=\dfrac{2^{29}.3^{18}.\left(5.2-3^2\right)}{2^{28}.3^{18}.\left(7.2-5.3\right)}\)
\(A=\dfrac{2.\left(10-9\right)}{14-15}=\dfrac{2}{-1}=-2\)
Chúc bạn học tốt!!!
\(A=\dfrac{5.4^{15}.9^9-4.3^{20}.8^9}{7.2^{29}.27^6-5.2^9.6^{19}}=\dfrac{5.\left(2^2\right)^{15}.\left(3^2\right)^9-2^2.3^{20}.\left(2^2\right)^9}{7.2^{29}.27^6-5.2^9.\left(2.3\right)^{19}}\)
\(=\dfrac{5.2^{30}.3^{18}-2^2.3^{20}.2^{27}}{7.2^{29}.3^{18}-5.2^9.2^{19}.3^{19}}\)
\(=\dfrac{2^{29}.3^{18}\left(5.2-3^2\right)}{2^{28}.3^{18}\left(7.2-5.3\right)}\)
\(=\dfrac{2\left(10-9\right)}{14-15}=\dfrac{2}{-1}=-2\)
a: \(A=\dfrac{3^3\cdot2^3+3^3\cdot2^2+3^3\cdot1}{-13}=\dfrac{27\left(2^3+2^2+1\right)}{-13}=-27\)
b: \(B=\dfrac{2\cdot2^{12}\cdot3^6+2^{11}\cdot3^9}{2^3\cdot2^7\cdot3^7+2^7\cdot2^3\cdot5\cdot3^8}\)
\(=\dfrac{2^{13}\cdot3^6+2^{11}\cdot3^9}{2^{10}\cdot3^7+2^{10}\cdot5\cdot3^8}\)
\(=\dfrac{2^{11}\cdot3^6\left(2^2+3^3\right)}{2^{10}\cdot3^7\left(1+5\cdot3\right)}=\dfrac{2}{3}\cdot\dfrac{4+27}{1+15}=\dfrac{2}{3}\cdot\dfrac{31}{16}=\dfrac{31}{24}\)
c: \(C=\dfrac{5\cdot2^{30}\cdot3^{18}-2^{29}\cdot3^{20}}{5\cdot2^{35}\cdot3^{19}-7\cdot2^{29}\cdot3^{18}}\)
\(=\dfrac{2^{29}\cdot3^{18}\left(5\cdot2-3^2\right)}{2^{29}\cdot3^{18}\left(5\cdot2^6-7\right)}=\dfrac{10-9}{5\cdot64-7}=\dfrac{1}{313}\)