100 . x + ( 10 + 2 ) = 212
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A = I x - 10 I + 100
Có I x - 10 I >= 0
=> I x - 10 I + 100 >= 100
=> A >= 100
Amin = 100
\(9,x-\sqrt{x}=\sqrt{x}\left(\sqrt{x}-1\right)\\ 10,a+3\sqrt{a}-10=\left(\sqrt{a}-1\right)\left(\sqrt{a}+5\right)\\ 11,x+\sqrt{x}-2=\left(\sqrt{x}-1\right)\left(\sqrt{x}+2\right)\\ 12,x-5\sqrt{x}+6=\left(\sqrt{x}-3\right)\left(\sqrt{x}-2\right)\)
9: \(x-\sqrt{x}=\sqrt{x}\left(\sqrt{x}-1\right)\)
10: \(a+3\sqrt{a}-10=\left(\sqrt{a}+5\right)\left(\sqrt{a}-2\right)\)
11: \(x+\sqrt{x}-2=\left(\sqrt{x}+2\right)\left(\sqrt{x}-1\right)\)
12: \(x-5\sqrt{x}+6=\left(\sqrt{x}-2\right)\left(\sqrt{x}-3\right)\)
\(^{212}_{84}Po\rightarrow^4_2He+_{82}^{208}Pb\)
\(m=m_02^{-\frac{t}{T}}\)
b/ Khi \(m=\frac{1}{2}m_0\Rightarrow\frac{1}{2}m_0=m_02^{-\frac{t}{T}}\Rightarrow2^{-\frac{t}{T}}=\frac{1}{2}=2^{-1}\)
\(\Rightarrow\frac{-t}{T}=-1\Rightarrow t=T=3.10^{-7}\left(s\right)\)
c/ Khi \(m=\frac{1}{8}m_0\Rightarrow\frac{1}{8}m_0=m_0.2^{-\frac{t}{T}}\Rightarrow2^{-\frac{t}{T}}=\frac{1}{8}=2^{-3}\)
\(\Rightarrow\frac{-t}{T}=-3\Rightarrow t=3T=9.10^{-7}\left(s\right)\)
d/ \(m=m_0.2^{-\frac{t}{T}}=100.2^{\frac{-12.10^{-7}}{3.10^{-7}}}=100.2^{-4}=\frac{100}{2^4}=6,25\left(g\right)\)
2 × 6 = 12 6 × 2 = 12 12 : 2 = 6 12 : 6 = 2 | 7 × 4 = 28 4 × 7 = 28 28 : 7 = 4 28 : 4 = 7 | 9 × 3 = 27 3 × 9 = 27 27 : 9 = 3 27 : 3 = 9 | 8 × 5 = 40 5 × 8 = 40 40 : 8 = 5 40 : 5 = 8 |
Bài làm
Sửa đề : \(\left(2x+3\right)-117=212\)( coppy lại đề nó vậy đấy, ko sao )
\(\Leftrightarrow2x+3=329\Leftrightarrow2x=326\Leftrightarrow x=163\)
(2x+ 3) - 117 = 212
=> 2x+ 3 = 212 + 171
2x+ 3 = 383
2x = 383 - 3
2x = 380
x = 380 : 2
x = 190
giúp mình nha
\(100.x+\left(10+2\right)=212\)
\(\Leftrightarrow100x+\left(10+2\right)=212\)
\(\Leftrightarrow10x+12=212\)
\(\Leftrightarrow10x=200\)
\(\Leftrightarrow x=20\)
100 . x + ( 10 + 2 ) = 212
100 . x + 12 = 212
100 . x = 212 - 12
100 . x = 200
x = 200 : 100
x = 2