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a: =7/8:(2/9-18+1/36)-5/12
=-7/142-5/12=-397/852
b: =3/7(4/9+5/9:6/12)=2/3
c: =5^8(16/31-47/31)+1/3=-5^8+1/3
d: =7/2(3/8+5/8:4/15)=609/64
Bài 1:
5; (-23) + 105
= 105 - 23
= 82
6; 78 + (-123)
= 78 - 123
= - (123 - 78)
= - 45
bài1
1)2763 + 152 = 2915
2)-7 +(-14)
=-(14 +7)
=-21
2,
a) \(315-\left(135-x\right)=215\)
\(\Rightarrow135-x=315-215\)
\(\Rightarrow135-x=100\)
\(\Rightarrow x=135-100\)
\(\Rightarrow x=35\)
b) \(x-320:32=25\cdot16\)
\(\Rightarrow x-10=5^2\cdot4^2\)
\(\Rightarrow x-10=20^2\)
\(\Rightarrow x-10=400\)
\(\Rightarrow x=410\)
c) \(3\cdot x-2018:2=23\)
\(=3\cdot x-1009=23\)
\(\Rightarrow3\cdot x=1032\)
\(\Rightarrow x=1032:3\)
\(\Rightarrow x=344\)
d) \(280-9\cdot x-x=80\)
\(\Rightarrow280-x\cdot\left(9+1\right)=80\)
\(\Rightarrow280-10\cdot x=80\)
\(\Rightarrow10\cdot x=280-80\)
\(\Rightarrow10\cdot x=200\)
\(\Rightarrow x=20\)
e) \(38\cdot x-12\cdot x-x\cdot16=40\)
\(\Rightarrow x\cdot\left(38-12-16\right)=40\)
\(\Rightarrow x\cdot10=40\)
\(\Rightarrow x=40:10\)
\(\Rightarrow x=4\)
\(7^6+7^5-7^4\)
\(=7^4\left(7^2+7-1\right)\)
\(=7^4\cdot55⋮55\)
\(16^5+2^5\)
\(=\left(2^4\right)^5+2^5\)
\(=2^{20}+2^5\)
\(=2^5\left(2^{15}+1\right)\)
\(=2^5\cdot32769⋮33\)
traa loi nhanh cho minh , minh can gap vao dem thu sau ngay 8 thang 11
Bài 1
a)(9+8)x + 16 . 2x = 98
17x + 32x = 98
49x = 98
x = 98 : 49
x = 2
\(a,\left(48\cdot0,75-240:10\right)-\left(16\cdot0,5-16:4\right)\)
\(=\left(48\cdot0,75-240\cdot0,1\right)-\left(16:2-16:4\right)\)
\(=\left(36-24\right)-\left(8-4\right)\)
\(=12-4=8\)
\(b,\left(\frac{1}{2}+\frac{3}{5}-\frac{2}{15}\right):\frac{3}{5}\)
\(=\left(\frac{11}{10}-\frac{2}{15}\right):\frac{3}{5}\)
\(=\frac{29}{30}:\frac{3}{5}=\frac{145}{90}=\frac{29}{18}\)
\(c,\left(\frac{13}{84}\cdot\frac{2}{5}-\frac{1}{2}\cdot\frac{7}{180}\right):\frac{27}{18}+\frac{1}{2}\cdot\frac{1}{10}\)
\(=\left(\frac{26}{420}-\frac{7}{360}\right):\frac{3}{2}+\frac{1}{20}\)
\(=\left(\frac{13}{210}-\frac{7}{360}\right):\frac{3}{2}+\frac{1}{20}\)
\(=\frac{107}{2520}:\frac{3}{2}+\frac{1}{20}\)
\(=\frac{214}{7560}+\frac{1}{20}=\frac{214}{7560}+\frac{378}{7560}\)
\(=\frac{592}{7560}=\frac{74}{945}\)
Trả lời:
a, \(\left(48\times0,75-240\div10\right)-\left(16\times0,5-16\div4\right)\)
\(=\left(36-24\right)-\left(8-4\right)\)
\(=12-4\)
\(=8\)
b,\(\left(\frac{1}{2}+\frac{3}{5}-\frac{2}{15}\right)\div\frac{3}{5}\)
\(=\left(\frac{11}{10}-\frac{2}{15}\right)\times\frac{5}{3}\)
\(=\frac{29}{30}\times\frac{5}{3}\)
\(=\frac{29}{18}\)
c,\(\left(\frac{13}{84}\times\frac{2}{5}-\frac{1}{2}\times\frac{7}{180}\right)\div\frac{27}{18}+\frac{1}{2}\times\frac{1}{10}\)
\(=\left(\frac{13}{210}-\frac{7}{360}\right)\times\frac{18}{27}+\frac{1}{2}\times\frac{1}{10}\)
\(=\frac{107}{2520}\times\frac{18}{27}+\frac{1}{20}\)
\(=\frac{107}{3780}+\frac{1}{20}\)
\(=\frac{74}{945}\)