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Bài 6.3
\(\dfrac{8}{11}\) = \(\dfrac{16}{22}\) = \(\dfrac{24}{33}\)
\(\dfrac{-5}{9}\) = \(\dfrac{-10}{18}\) = \(\dfrac{-15}{27}\)
Bài 6.4
\(\dfrac{-12}{-4}\) = \(\dfrac{-12:\left(-4\right)}{-4:\left(-4\right)}\) = \(\dfrac{3}{1}\)
\(\dfrac{7}{-35}\) = \(\dfrac{7:\left(-7\right)}{-35:\left(-7\right)}\) = \(\dfrac{-1}{5}\)
\(\dfrac{-9}{27}\) = \(\dfrac{-9:9}{27:9}\) = \(\dfrac{-1}{3}\)
\(6.3\\ \dfrac{8}{-11}=\dfrac{8.\left(-1\right)}{\left(-11\right).\left(-1\right)}=\dfrac{-8}{11};\dfrac{-5}{-9}=\dfrac{-5:\left(-1\right)}{\left(-9\right):\left(-1\right)}=\dfrac{5}{9}\\ --\\ 6.4\\ \dfrac{-12}{4}=\dfrac{-12:4}{4:4}=-3\\ \dfrac{7}{-35}=\dfrac{7:\left(-7\right)}{-35:\left(-7\right)}=-\dfrac{1}{5}\\ \dfrac{-9}{27}=\dfrac{-9:9}{27:9}=\dfrac{-1}{3}\)
\(6.5\\ 15p=\dfrac{15}{60}\left(h\right)=\dfrac{15:15}{60:15}\left(h\right)=\dfrac{1}{4}\left(h\right)\\ 90p=\dfrac{90}{60}\left(h\right)=\dfrac{90:30}{60:30}\left(h\right)=\dfrac{3}{2}\left(h\right)\)
\(6.3^2+8^7:8^5-1^{2020}\)
\(=6.9+8^2-1\)
\(=54+64-1\)
\(=118-1\)
\(=117\)
\(6\cdot3^2+8^7:8^5-1^{2020}\)
\(=6\cdot9+8^{7-5}-1\)
\(=54+8^2-1\)
\(=53+64\)
\(=117\)
\(\frac{9}{6}.\frac{6}{7}+\frac{9}{6}.\frac{4}{5}\)
\(=\frac{9}{6}\left(\frac{6}{7}+\frac{4}{5}\right)\)
\(=\frac{9}{6}\left(\frac{30}{35}+\frac{28}{35}\right)\)
\(=\frac{3}{2}.\frac{58}{35}\)
\(=\frac{174}{70}\)
\(=\frac{87}{35}\)
Câu 1 xem kỉ đề
\(B,\frac{49^6.5-7^{11}}{\left(-7\right)^{10}.5-2.49^5}=\frac{7^{12}.5-7^{11}}{7^{10}.5-2.7^{10}}=\frac{7^{11}.\left(7.5-1\right)}{7^{10}.\left(5-2\right)}=\frac{7.34}{3}=\frac{238}{3}\)
a) A=212.35-\(\frac{2^{12}.3^6}{2^{12}}\)+93+84.35
=212.35-36+36+212.35
=213.35
b)B=496.5-5.\(\frac{7^{11}}{\left(-7\right)^{10}}-2.49^5\)
=496.5-7.5-2.495
=712.5-7.5-2.710
Câu 1: 2 bài đầu hình như đề sai.
\(-\dfrac{5}{6}.\dfrac{4}{17}+-\dfrac{7}{12}.\dfrac{4}{7}\)
\(=\dfrac{4}{7}.\left(-\dfrac{5}{6}+-\dfrac{7}{12}\right)\)
\(=\dfrac{4}{7}.\dfrac{-17}{12}\)
\(=-\dfrac{1}{3}\)
Câu 2:
\(\dfrac{4}{5}.x=125\%-0,25\)
\(\dfrac{4}{5}.x=\dfrac{5}{4}-\dfrac{1}{4}\)
\(\dfrac{4}{5}.x=1\)
\(\Rightarrow\) \(x=1:\dfrac{4}{5}\)
\(\Rightarrow\) \(x=\dfrac{5}{4}\)
Vậy \(x=\dfrac{5}{4}\)
a) \(3^6.3^7\) \(=3^{13}\)
b) \(x^{10}:x^6:x\)
\(=x^{10}:x^7\)\(=x^3\)
c) \(a^5.a^9=a^{14}\)
\(a,=3^{6+7}=3^{13}\\ b,=x^{10-6-1}=x^3\\ c,=a^{5+9}=a^{14}\\ d,=2^3\cdot2^{15}\cdot2^{16}=2^{34}\\ e,=5^6\cdot5^5\cdot5^5=5^{16}\\ f,=a^{10+4-12}=a^2\)
giup minh voi