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0,5.40-0,5.20.8.0,1.0,25.10/128:8.16.(4+52:4)=20-0,3125.17=20-5,3125=14,6875
nhớ k cho mik nhoa!
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\(18+22\cdot13-8\cdot16-\left(92\cdot16-22\cdot87\right)\)
\(=18+22\cdot13-8\cdot16-92\cdot16+22\cdot87\)
\(=22\cdot\left(13+87\right)-16\cdot\left(8+92\right)+18\)
\(=22\cdot100-16\cdot100+18\)
\(=2200-1600+18\)
\(=600+18\)
\(=618\)
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\(8.16\ge2^n\ge4\) => \(2^3.2^4\ge2^n\ge2^2\)=> \(2^7\ge2^n\ge2^2\)
=> \(7\ge n\ge2\)
=> \(n\in\left\{2;3;4;5;6;7\right\}\)
\(8.16\ge2^n\ge4\)
\(\Leftrightarrow2^3.2^4\ge2^n\ge2^2\)
\(\Leftrightarrow2^7\ge2^n\ge2^2\)
\(\Rightarrow2\le n\le7\)
\(\Rightarrow n\varepsilon\left\{2;3;4;5;6;7\right\}\)
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a ) ( -1/6 + 5/12 ) + 7/12
= -1/6 + ( 5/12 + 7/12 )
= -1/6 + 12/12
= -2/12 + 12/12
= -10/12
= -5/6
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\(\frac{2048^2.2^{11}.8^6.64^7.128^3}{1024^4.4^8.16^7.2^{30}}=\frac{2^{22}.2^{11}.2^{18}.2^{42}.2^{21}}{2^{40}.2^{16}.2^{28}.2^{30}}=\frac{2^{114}}{2^{114}}=1\)
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\(a)196:4-12.\left(-5\right)=49+60=109.\\ b)2^2.5+\left(49-17^2\right)=4.5+49-289=20-240=-220.\\ c)29.\left(15-34\right)-15.\left(29-34\right)=29.15-29.34-15.29+15.34=-29.34+15.34=-476.\)
Bài 2:
Gọi số sách là x
Theo đề, ta có: \(x\in BC\left(10;12;15\right)\)
mà 100<=x<=150
nên x=120
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\(\left(x-15\right)\cdot\frac{7}{45}=196\)
\(x-15=196:\frac{7}{45}\)
x - 15 = 1260
x = 1275
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mình nghĩ là đề như vậy:
\(\frac{24}{8.16}-\frac{40}{16.24}+\frac{56}{24.32}-\frac{72}{32.40}=\frac{8+16}{8.16}-\frac{16+24}{16.24}+\frac{24+32}{24.32}-\frac{32+40}{32.40}\)
\(=\frac{8}{8.16}+\frac{16}{8.16}-\frac{16}{16.24}-\frac{24}{16.24}+\frac{24}{24.32}+\frac{32}{24.32}-\frac{32}{32.40}-\frac{40}{32.40}\)
\(=\frac{1}{16}+\frac{1}{8}-\frac{1}{24}-\frac{1}{16}+\frac{1}{32}+\frac{1}{24}-\frac{1}{40}-\frac{1}{32}\)
\(=\frac{1}{8}-\frac{1}{40}=\frac{1}{10}\)
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\(\frac{2}{1.4}+\frac{2}{4.7}+\frac{2}{7.9}+...+\frac{2}{196.199}=\frac{2}{3}\left(\frac{3}{1.4}+\frac{3}{4.7}+\frac{3}{7.9}+...+\frac{3}{196.199}\right)\)
\(=\frac{2}{3}\left(1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}+...+\frac{1}{196}-\frac{1}{199}\right)\)
\(=\frac{2}{3}\left(1-\frac{1}{199}\right)\)
\(=\frac{2}{3}.\frac{198}{199}\)
\(=\frac{132}{199}\)