2.3 MŨ 2 - 4 MŨ 3 : (16.2)
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a)
\(\text{( 25 – 2x )³ : 5 – 3^2 = 4^2}\)
\(\text{( 25 – 2x )³ : 5 – 9 = 16}\)
\(\text{( 25 – 2x )³ : 5 = 16 + 9}\)
\(\text{( 25 – 2x )³ : 5 = 25}\)
\(\text{( 25 – 2x )³ = 25 . 5}\)
\(\text{( 25 – 2x )³ = 125}\)
\(\text{( 25 – 2x )³ = 5³}\)
\(\text{25 – 2x = 5}\)
\(\text{2x = 25 – 5}\)
\(\text{2x = 20}\)
\(\text{x = 10}\)
\(\text{________________________________________}\)
b)
\(\text{2.3^x = 10.3^12 + 8.27^4}\)
\(\text{2.3^x = 10.3^12 + 8.(3^3)^4}\)
\(\text{2.3^x = 3^12 . (10+8)}\)
\(\text{2.3^x = 3^12 . 18}\)
\(\text{3^x = 3^12 . 18:2}\)
\(\text{3^x = 3^12 . 9}\)
\(\text{3^x = 3^12 . 3^2}\)
\(\text{3^x = 3^14}\)
\(\text{=> x=14}\)
\(\dfrac{1}{2}\cdot\dfrac{3}{4}=\dfrac{3}{8}\\ \left(\dfrac{1}{2}\right)^3\cdot\left(\dfrac{3}{4}\right)^3=\left(\dfrac{1}{2}\cdot\dfrac{3}{4}\right)^3=\left(\dfrac{3}{8}\right)^3\\ \dfrac{3}{8}< \left(\dfrac{3}{8}\right)^3\Rightarrow\dfrac{1}{2}\cdot\dfrac{3}{4}< \left(\dfrac{1}{2}\right)^3\cdot\left(\dfrac{3}{4}\right)^3\)
(1981 x 1982 - 990) : (1980 x 1982 + 992)
=(1980 x 1982+1982 -990) : (1980 x 1982 +992)
=(1980 x 1982 + 992) : ( 1980 x 1982 + 992)
=1
B=[(45.79+45.21)]:90-5^2]:5+2^3 B=[(45.79+45.21):90-25]:5+8 B=[(45.(79+21):65]:13 B=[(45.100):65]:13 B=[4500:65]:13 B=4500:65:13
205 - [ 1200 - ( 42 - 2 . 3 )3 ] : 40
= 205 - [ 1200 - ( 16 - 2 . 3 )3 ] : 40
= 205 - [ 1200 - ( 16 - 6 )3 ] : 40
= 205 - [ 1200 - 103 ] : 40
= 205 - [ 1200 - 1000 ] : 40
= 205 - 200 : 40
= 205 - 5
= 200