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a, Ta có: 339 < 340 = (32)20 = 920
1121 > 1120
Vì 9 < 11 => 920 < 1120 => 339 < 1121
b, Ta có: 1245 - 1244 = 1244(12 - 1) = 1244.11
1244 - 1243 = 1243(12 - 1) = 1243.11
Vì 1244 > 1243 => 1244.11 > 1243.11 => 1245 - 1244 > 1244 - 1243
c, Đặt A = 1+2+22+....+29
2A = 2+22+23+...+210
2A-A=210-1
A=210-1
Ta có: 5.28 = 28.4 > 28.4 - 1 = 210 - 1
Vậy A < 5.28
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a,(-67.77) - (-67.44) - 77.44+77.67
= (-67).(77-44)-77.(44+67)
= (-67-77).(77-44+44+67)
=-144.144
=-20736
b,[-36:(-12)]-12.8+63-1
=3-12.8+216-1
=3-96+216-1
=122
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1: 243^5=(3^5)^5=3^25
3*27^8=3*(3^3)^8=3^25
=>243^5=3*27^8
6: 125^5=(5^3)^5=5^15
25^7=(5^2)^7=5^14
=>125^5>25^7(15>14)
5: 78^12-78^11=78^11(78-1)=78^11*77
78^11-78^10=78^10*77
mà 11>10
nên 78^12-78^11>78^11-78^10
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\(25-\left(44-756+12\right)+\left(44-756+12\right)\)
\(=25-44+756-12+44-756+12\)
\(=25+\left(44-44\right)+\left(756-756\right)+\left(12-12\right)\)
=25
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a) \(\left(x-2\right)^2-11=25\)
\(\left(x-2\right)^2=25+11\)
\(\left(x-2\right)^2=36\)
\(\left(x-2\right)^2=6^2\)
\(\Rightarrow x-2=6\)
\(\Rightarrow x=8\)
vậy \(x=8\)
những câu khác làm tương tự
học vui truong the dat
a, \(\left(x-2\right)^2-11=25\)
\(\Rightarrow\left(x-2\right)^2=25+11\)
\(\Rightarrow\left(x-2\right)^2=36\)
\(\Rightarrow\left(x-2\right)^2=6^2=\left(-6\right)^2\)
\(\Rightarrow x-2=6\)hoặc \(x-2=-6\)
\(\Rightarrow x\in\left\{8;-4\right\}\)
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giải nhanh và chính xác giùm mừn nha, iu các pạn nhìu.......
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a) \(21^{15}=21^{3.5}=\left(21^3\right)^5=9261^5\)
Vì \(9261>27\Rightarrow9261^5>27^5\Rightarrow21^{15}>27^5\)
b) \(15^{12}=\left(3.5\right)^{12}=3^{12}.5^{12}\)
\(81^3.125^5=\left(3^4\right)^3.\left(5^3\right)^5=3^{4.3}.5^{3.5}=3^{12}.5^{15}\)
Vì \(3^{12}=3^{12}\)mà \(5^{12}< 5^{15}\Rightarrow3^{12}.5^{12}< 3^{12}.5^{15}\Rightarrow15^{12}< 81^3.125^5\)
(-12 - 44) + (-3) = -56+ (-3 ) = -59
\(\left(-12-44\right)+\left(-3\right)\)
\(=-56+\left(-3\right)\)
\(=-59\)