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a)[(-15).8]:4
=-120:4
=30
b)[(-125):(-5)].(-13)
=25.(-13)
=325
A = (-25).8.2.5.(-4).13 = [(-25).(-4)].8.2.5.13 = 100.8.10.13 = 10400
B = 13.(-7) + (-13).57 + 13.(-36) = 13.(-7) - 13.57 + 13.(-36)
= 13.[(-7) + (-57) + (-36)]
= 13. (-100)
= -1300
Ta có: \(A=\left(-25\right)\cdot8\cdot2\cdot5\cdot\left(-4\right)\cdot13\)
\(=\left[\left(-25\right)\cdot\left(-4\right)\right]\cdot\left(2\cdot5\right)\cdot\left(8\cdot13\right)\)
\(=104000\)
Ta có: \(B=13\cdot\left(-7\right)+\left(-13\right)\cdot57+13\cdot\left(-36\right)\)
\(=13\cdot\left(-7\right)-13\cdot57-13\cdot36\)
\(=13\left(-7-57-36\right)\)
\(=13\cdot\left(-100\right)=-1300\)
a) 24 +117 + 115 + 176 + 83
=(24+176)+(117+83)+115
= 200+200+115
=515
b) 17.57 + 43.17 + 29
=17.(57+43)+29
=17.100+29
=1700+29
=1729
c) 47.164 + 164.53 + 5 . 43
=164.(47+53)+5.64
=164.100+320
=16400+320
=16720
d)194.12 + 6.437.2 + 3.369.4
=194.12 + 437.12 + 369.12
=12.(194+437+369)
=12.1000
=12000
Ta có :
\(\left|x-2^{2015}\right|\ge0\)
\(\left|x-2^{2015}\right|+2\ge2\)
\(\Rightarrow Min_A=2\)
Bài 5:
a) Ta có: \(A=1\cdot2+2\cdot3+3\cdot4+...+9\cdot10\)
\(\Leftrightarrow3\cdot A=3\cdot\left(1\cdot2+2\cdot3+3\cdot4+...+9\cdot10\right)\)
\(\Leftrightarrow3A=1\cdot2\cdot\left(3-0\right)+2\cdot3\cdot\left(4-1\right)+3\cdot4\cdot\left(5-2\right)+...+9\cdot10\cdot\left(11-8\right)\)
\(\Leftrightarrow3A=1\cdot2\cdot3+2\cdot3\cdot4-1\cdot2\cdot3+3\cdot4\cdot5-2\cdot3\cdot4+...+8\cdot9\cdot10-8\cdot9\cdot10+9\cdot10\cdot11\)
\(\Leftrightarrow3\cdot A=9\cdot10\cdot11=90\cdot11=990\)
hay A=330
Vậy: A=330
b: \(N=3x-2y+5x-y-7y+2x=10x-10y=10\cdot\left(x-y\right)=0\)
\(a,M=12-x+x-73+96+x-23=x+12\\ M=101+12=113\\ b,N=3x-2y+5x-y-7y+2x=10x-10y\\ N=10\cdot2021-10\cdot2021=0\)
\(A=\frac{3^{10}\cdot11+3^{10}\cdot5}{3^9\cdot2^4}\)
\(=\frac{3^{10}\left(11+5\right)}{3^9\cdot2^4}=\frac{3^{10}.16}{3^9.16}=3\)
\(\frac{3^{10}.11+3^{10}.5}{3^9.2^4}=\frac{3^{10}.16}{3^9.16}\)
\(=\frac{3^{10}}{3^9}=3\)
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