1)
A) 47,57 . 12,38 + 12,38 . 52,43
B) 5/15 + 14/25 – 12/9 + 2/7 + 11/25
2)
a) x – 1/4 = 23/14
B) |2,5 – x|= 1,3
C) so sánh 2 mũ 225 và 3 mũ 150
1)
A) 47,57 . 12,38 + 12,38 . 52,43
B) 5/15 + 14/25 – 12/9 + 2/7 + 11/25
2)
a) x – 1/4 = 23/14
B) |2,5 – x|= 1,3
C) so sánh 2 mũ 225 và 3 mũ 150
`1`
$a)47,57.12,38+12,38.52,43$
$=12,38(47,57+52,43)$
$=12,38.100$
$=1238$
$b)\dfrac{5}{15}+\dfrac{14}{25}-\dfrac{12}{9}+\dfrac{2}{7}+\dfrac{11}{25}$
`=\frac{1}{3}+(\frac{14}{25}+\frac{11}{25})-\frac{12}{9}+\frac{2}{7}`
`=1/3+1-4/3+2/7`
`=(1/3-4/3)+1+2/7`
`=-1+1+2/7`
`=0+2/7`
`=2/7`
`2`
`a)` `x-1/4=23/14`
`x=23/14-1/4`
`x=53/28`
`b)` `|2,5-x|=1,3`
`=>`\(\left[ \begin{array}{l}2,5-x=1,3\\2,5-x=-1,3\end{array} \right.\) `=>`\(\left[ \begin{array}{l}x=1,2\\x=3,8\end{array} \right.\)
`c)` `2^{225}=(2^3)^{75}=8^{75}`
`3^{150}=(3^2)^{75}=9^{75}`
Vì `8^{75}<9^{75}` nên $2^{225}<3^{150}$.
#KhanhHuyen2006 – Xin câu trả lời hay nhất
Bài 1
`a) 47,57 . 12,38 + 12,38 . 52,43`
`= 12,38 . (47,57 + 52,43)`
`= 12,38 . 100`
`= 1238`
`b) 5/15 + 14/25 – 12/9 + 2/7 + 11/25`
`= 67/75 – 12/9 + 2/7 + 11/25`
`= -11/25 + 2/7 + 11/25`
`= -27/175 + 11/25`
`= 2/7`
Bài 2
`a) x – 1/4 = 23/14`
`-> x = 23/14 + 1/4`
`-> x = 53/28`
`b) |2,5 – x| = 1,3`
`->` \(\left[ \begin{array}{l}2,5 – x = 1,3\\2,5 – x = -1,3\end{array} \right.\)
`->` \(\left[ \begin{array}{l}x=1,2\\x=3,8\end{array} \right.\)
`c)`
Ta có : `2^{225} = (2^{15})^{15} = 32768^{15}`
Ta có : `3^{150} = (3^{10})^{15} = 59049^{15}`
`-> 32768 < 59049`
`-> 2^{225} < 3^{150}`