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42-56+33-(33-56+42)
=42-56+33-33+56-42
=0
54-(45-30+54)-30+5
=54-45+30-54-30+5
=-40
Bài 1: So sánh
a)\(^{56^{56}-56^{56}}\)và \(^{56^{56}-56^{54}}\)
b)\(3^5.7^{15}\) và \(27^5.7^{16}\)
a, ta có:VT=0 \(\Rightarrow56^{56}-56^{56}< 56^{56}-56^{54}\)
b,Ta có:\(27^5.7^{16}=(3^3)^5.7^{16}\)\(\Leftrightarrow3^{15}.7^{16}\)
nhận thấy:\(3^5< 3^{15}\);\(7^{15}< 7^{16}\)
\(\Rightarrow3^5.7^{15}< 27^5.7^{16}\)
\(\frac{\frac{3}{67}.\left(17\frac{21}{56}-13\frac{21}{45}\right):\left(\frac{3}{5.22}+\frac{54}{44.65}+\frac{18}{65.72}\right)}{29^3:100-29^3:0,47}\)
\(=\frac{\frac{3}{67}\left(\frac{139}{8}-\frac{202}{15}\right):\left(\frac{3}{110}+\frac{54}{2860}+\frac{18}{4680}\right)}{29^3.\frac{1}{100}-29^3.\frac{47}{100}}\)
\(=\frac{\frac{3}{67}.\frac{469}{120}:\frac{1}{20}}{29^3\left(\frac{1}{100}-\frac{47}{100}\right)}\)
\(=\frac{\frac{7}{40}.20}{29^3.\left(-\frac{23}{50}\right)}\).
\(=\frac{\frac{7}{2}}{-11218,94}\)
\(=-\frac{175}{560947}\)
Bài 1:
a. Ta có: $1953=3^2.7.31$
$777=3.7.37$
$\Rightarrow UCLN(1953, 777) = 3.7=21$
b. Đề khó hiểu quá. Bạn xem lại/
Bài 2: Thiếu dấu giữa các số. Bạn xem lại.
\(B=\left(4^5\cdot10\cdot5^6+25^5\cdot2^8\right):\left(2^8\cdot5^4+5^7\cdot2^5\right)\)
\(B=\dfrac{4^5\cdot10\cdot5^6+25^5\cdot2^8}{2^8\cdot5^4+5^7\cdot2^5}\)
\(B=\dfrac{\left(2^2\right)^5\cdot2\cdot5\cdot5^6+\left(5^2\right)^5\cdot2^8}{2^8\cdot5^4+5^7\cdot2^5}\)
\(B=\dfrac{2^{11}\cdot5^7+5^{10}\cdot2^8}{2^8\cdot5^4+5^7\cdot2^5}\)
\(B=\dfrac{2^8\cdot5^7\cdot\left(2^3\cdot1+5^3\cdot1\right)}{2^5\cdot5^4\cdot\left(2^3\cdot1+5^3\cdot1\right)}\)
\(B=\dfrac{2^8\cdot5^7}{2^5\cdot5^4}\)
\(B=\dfrac{2^3\cdot5^3}{1\cdot1}\)
\(B=\left(2\cdot5\right)^3\)
\(B=10^3\)
\(B=1000\)
a) Ta có: \(54⋮x;120⋮x;180⋮x\Rightarrow x\inƯC\left(54;120;180\right)\) \(\left(x\in N\right)\)
\(\Rightarrow x=\left\{1;2;3;6\right\}\)
b) Theo đề bài \(\Rightarrow x-3\inƯC\left(45;54\right)\left(x\in N\right);\left(x>9\right)\)
\(\Rightarrow x-3=9\Rightarrow x=12\)
c) Tương tự
Ta có: \(2\left(x+45\right)-54=-56\)
=>\(2\left(x+45\right)=-56+54=-2\)
=>x+45=-1
=>x=-46
2(x+45)-54=-56
2(x+45) = -56 + 54
2(x+45) = (-2)
(x+45) = (-2) + 2
(x+45) = 0
x = 0 -45
x = -45