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\(a.13-18-\left(-42\right)-15\)
\(=-5-\left(-42\right)-15\)
\(=37-15\)
\(=22\)
\(b.\left(-8\right)^3:\left(-8^2\right)-8\)
\(=-8-8\)
\(=-16\)
\(\left(-20\right)+99-121+\left|-20\right|\)
\(=\left(-20\right)+99-121+20\)
\(=\left[\left(-20\right)+20\right]+\left[99-121\right]\)
\(=0+\left(-22\right)\)
\(=-22\)
1)
a) Bằng nhau.Vì\(\frac{-3}{5}=\frac{-9}{15}=\frac{9}{-15}=\frac{-9}{15}\)
b) Không bằng.Vì \(\frac{4}{3}=\frac{12}{9}>\frac{-12}{9}\)
2)
a).\(\frac{-2}{3}+\frac{4}{15}=\frac{-10}{15}+\frac{4}{15}=\frac{-6}{15}=-\frac{2}{5}\)
b) \(\frac{-9}{5}:\frac{3}{5}=\frac{-9}{5}x\frac{5}{3}=\frac{-45}{15}=-3\)
c) \(\frac{3}{7}x\frac{5}{11}+\frac{3}{7}x\frac{6}{11}=\frac{3}{7}x\left(\frac{5}{11}+\frac{6}{11}\right)=\frac{3}{7}x\frac{11}{11}=\frac{3}{7}x1=\frac{3}{7}\)
3)
a) 2x + 23 = 2016-(17+2016)
2x + 23 = 2016-17 + 2016 -2016
2x + 23 = 1999
2x = 1976
x = 988
b)
\(\frac{-2}{5}.x=2\)
\(x=2:\frac{-2}{5}\)
\(x=-5\)
- Học Tốt -
\(4.5^5-32:2^4\)
\(=4.5^5-2^5:2^4\)
\(=4.5^5-2^1\)
\(=4.3125-2\)
\(=12500-2\)
\(=12498\)
học tốt
4.55-32:24= 4. 5 . 54-25 : 24
= 20 . 54 -2= 20. 625-2=12500-2=12498
-17.(13+5) - 13.(17-2)
=-17.13+(-17).5-13.17+13.2
=-17.13+(-17).5 + 13 . (-17) + 13.2
=-17.(13+5+13) + 13.2
=-17. 31 +26
=-501
244.34-3212:1612
=(24.3)4-(32:16)12
=724-212
=26873856-4096
=26869760.
V )x+(x+1)+(x+2)+....+(x+30)=1240
31 . x + (1 + 2 + 3 + 4 +...+ 29 + 30) = 1240
31 . x + 31.15 = 1240
31 . x = 1240 - 31.15
31 . x = 775
x = 775 : 31
x = 25
\(\text{ -(-23) + (-36) + |57| - (-29)}\)
\(23+\left(-36\right)+57+29\)
\(=\left(23+57\right)+\left(\left(-36\right)+29\right)\)
\(=100+\left(-7\right)\)
\(=93\)
học tốt
\(2^5-500:25+3^2\cdot2^3\\ =32-20-9\cdot8\\ =12+72\\ =84\)
( 2^5 . 2^3 ) - 500 : 25 + 3^2 = 2^8 - 20 + 3^2
= ( 8^2 - 3^2 )+ 20 = 5^2 + 20 = 25+20 = 45