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a ) 87 . ( − 2 0 ) < | 87 . ( − 2 0 ) |
b ) 87 . ( − 2 0 ) = 87 . ( − 2 0 )
c ) 87 . ( − 2 0 ) = − | − 87 . 2 0 |
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a. Quy đồng: \(BCNN\left(92,107\right)=9844\)
\(\Rightarrow\dfrac{87}{92}=\dfrac{9309}{9844};\dfrac{102}{107}=\dfrac{9384}{9844}\)
Do \(\dfrac{9309}{9844}< \dfrac{9384}{9844}\)
Vậy: \(\dfrac{87}{92}< \dfrac{102}{107}\)
b. Quy đồng: \(BCNN\left(60,17\right)=1020\)
\(\Rightarrow\dfrac{-61}{60}=\dfrac{-1037}{1020};\dfrac{16}{17}=\dfrac{960}{1020}\)
Do: \(\dfrac{-1037}{1020}< \dfrac{960}{1020}\)
Vậy: ...
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\(\frac{93}{32}và\frac{87}{24}\)
Ta có:\(\frac{87}{24}=\frac{29}{8}\)\(=\frac{116}{32}\)
Vì \(\frac{93}{32}
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87 - (73 - \(x\)) = 20
87 - 73+ \(x\) = 20
14+ \(x\) = 20
\(x\) = 20 - 14
\(x\) = 6
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a)
(-12)(-13)+13(-22) = 12.13 - 13.22 = 13(12-22)=13.(-10)=-130
b) 15(-14) +15(-6) + (-20).25 = 15[(-14)+(-6)]+(-20).25=15.(-20)+(-20).25=(-20)(15+25)=-20.40=-800
c) -65.(87-17)-87(17-65) =
a)(-12).(-13)+13.(-22)=12.13+13.(-22)=13.[12+(-22)]=13.(-10)=-130
b)15.(-14)+15.(-6)+(-20).25=15.[(-14)+(-6)]+(-20).25=15.(-20)+(-20).25=(-20).(15+25)=(-20).40=-800
c)-65.(87-17)-87.(17-65)=-65.87-(-65).17-87.17+87.65
=-65.87+65.17-87.17+87.65
=[(-65)+65].87+(65-87).17
=0.87+(-22).17
=0+(-374)=-374
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Sửa đề: B=11^87+1/11^88+1
\(11A=\dfrac{11^{90}+11}{11^{90}+1}=1+\dfrac{10}{11^{90}+1}\)
\(11B=\dfrac{11^{88}+11}{11^{88}+1}=1+\dfrac{10}{11^{88}+1}\)
mà 11^90>11^88
nên A<B
87.(-20) < |87. (-20)|