1. Thực hiện phép tính
a) \(\frac{3}{4}.26\frac{1}{5}-\frac{3}{4}.44\frac{1}{5}\)
b)\(-\sqrt{25+2}\sqrt{16}\)
2. Tìm x, biết
a) 2 + x = - 5
b)\(\xrightarrow[x+5]{x-1}=\frac{6}{7}\)
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18 tháng 10 2018
\(3\frac{1}{2}-\frac{1}{2}.\left(-4,25-\frac{3}{4}\right)^2:\frac{5}{4}\)
\(=\frac{7}{2}-\frac{1}{2}.\left(-4,25-0,75\right)^2:\frac{5}{4}\)
\(=\frac{7}{2}-\frac{1}{2}.\left(-5\right)^2:\frac{5}{4}\)
\(=\frac{7}{2}-\frac{1}{2}.5.\frac{4}{5}\)
\(=\frac{7}{2}-2\)
\(=\frac{7}{2}-\frac{4}{2}\)
\(=\frac{3}{2}\)
\(\frac{3}{7}.1\frac{1}{2}+\frac{3}{7}.0,5-\frac{3}{7}.9\)
\(=\frac{3}{7}.\left(\frac{3}{2}+\frac{1}{2}-9\right)\)
\(=\frac{3}{7}.\left(2-9\right)\)
\(=\frac{3}{7}.\left(-7\right)\)
\(=-3\)
\(\frac{125^{2016}.8^{2017}}{50^{2017}.20^{2018}}=\frac{\left(5^3\right)^{2016}.\left(2^3\right)^{2017}}{\left(5^2\right)^{2017}.2^{2017}.\left(2^2\right)^{2018}.5^{2018}}=\frac{\left(5^3\right)^{2016}.\left(2^3\right)^{2017}}{\left(5^3\right)^{2017}.\left(2^3\right)^{2017}.2.5}=\frac{1}{5^4.2}=\frac{1}{1250}\)( tính nhẩm, ko chắc đúng )
18 tháng 10 2018
1
a) \(3\frac{1}{2}-\frac{1}{2}\cdot\left(-4,25-\frac{3}{4}\right)^2\) : \(\frac{5}{4}\)
= \(3\cdot25:\frac{5}{4}\)
= \(3\cdot\left(25:\frac{5}{4}\right)\)
=\(3\cdot20\)
=60
b)=\(\frac{3}{7}\cdot\left(1\frac{1}{2}+0,5-9\right)\)
=\(\frac{3}{7}\cdot\left(-7\right)\)
=\(-3\)
c) =
TV
18 tháng 8 2016
a, = \(\frac{\sqrt{7}-5}{2}-\frac{2\left(3-\sqrt{7}\right)}{4}+\frac{6\left(\sqrt{7}+2\right)}{\left(\sqrt{7}-2\right)\left(\sqrt{7}+2\right)}-\frac{5\left(4-\sqrt{7}\right)}{\left(4-\sqrt{7}\right)\left(4+\sqrt{7}\right)}\)
1a, 34.26.15−34.44.15=34.15.(26−44)=320.(−18)=−271034.26.15−34.44.15=34.15.(26−44)=320.(−18)=−2710
b,−√25+2√16=−√27.4=−4√27−25+216=−27.4=−427
2a, 2+x=-5
=>x=-7
b, x−1x+5=67=>7(x−1)=6(x+5)=>7x−7=6x+30=>x=37
1a, \(\frac{3}{4}.26.\frac{1}{5}-\frac{3}{4}.44.\frac{1}{5}=\frac{3}{4}.\frac{1}{5}.\left(26-44\right)=\frac{3}{20}.\left(-18\right)=\frac{-27}{10}\)
b,\(-\sqrt{25+2}\sqrt{16}=-\sqrt{27}.4=-4\sqrt{27}\)
2a, 2+x=-5
=>x=-7
b, \(\frac{x-1}{x+5}=\frac{6}{7}\\ =>7\left(x-1\right)=6\left(x+5\right)\\ =>7x-7=6x+30\\ =>x=37\)