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Đáp án cần chọn là: D
A = 25 . 9 − 25 . 17 − 8 . 80 − 8.10 = 25. ( 9 − 17 ) − 8. ( 80 + 10 ) = 25. ( − 8 ) ( − 8 ) .90 = 25 90 = 5 18 B = 48.12 − 48.15 − 3.270 − 3.30 = 48. ( 12 − 15 ) ( − 3 ) . ( 270 + 30 ) = 48. ( − 3 ) ( − 3 ) .300 = 48 300 = 4 25
Vì A < 1 nên loại đáp án C.
So sánh A và B:
MSC = 450
5 18 = 5.25 18.25 = 125 450 ; 4 25 = 4.18 25.18 = 72 450
Vì 125 > 72 nên 125 450 > 72 450 hay 5 18 > 4 25
Vậy A > B
\(\dfrac{25.9-25.17}{-8.80-8.10}=\dfrac{25.\left(9-17\right)}{-8.\left(80+10\right)}=\dfrac{25.\left(-8\right)}{-8.90}=\dfrac{25}{90}=\dfrac{5}{18}\)
\(\dfrac{48.12-48.15}{-3.270-3.30}=\dfrac{48.\left(12-15\right)}{-3.\left(270+30\right)}=\dfrac{48.\left(-3\right)}{-3.300}=\dfrac{48}{300}=\dfrac{4}{25}\)
MC = 450
\(\dfrac{5}{18}=\dfrac{5.25}{18.25}=\dfrac{125}{450}\)
\(\dfrac{4}{25}=\dfrac{4.18}{25.18}=\dfrac{72}{450}\)
25.9−25.17−8.80−8.10=25.(9−17)−8.(80+10)=25.(−8)−8.90=2590=51825.9−25.17−8.80−8.10=25.(9−17)−8.(80+10)=25.(−8)−8.90=2590=518
48.12−48.15−3.270−3.30=48.(12−15)−3.(270+30)=48.(−3)−3.300=48300=42548.12−48.15−3.270−3.30=48.(12−15)−3.(270+30)=48.(−3)−3.300=48300=425
MC = 450
518=5.2518.25=125450518=5.2518.25=125450
((25.9 - 25.17))(( - 8.80 - 8.10)) ) và ((48.12 - 48.15))(( - 3.270 - 3.30)) ). hãy so sánh 2 phân số trên
a) \(\frac{25.9-25.17}{-8.80-8.10}=\frac{25.\left(9-17\right)}{-8.\left(80+10\right)}=\frac{25.\left(-8\right)}{-8.90}=\frac{5}{18}\)
b) \(\frac{48.12-48.15}{-3.270-3.30}=\frac{48.\left(12-15\right)}{-3.\left(270+30\right)}=\frac{48.\left(-3\right)}{-3.300}=\frac{4}{25}\)
c) \(\frac{2^5.7+2^5}{2^5.5^2-2^5.3}=\frac{2^5.\left(7+1\right)}{2^5.\left(5^2-3\right)}=\frac{2^5.8}{2^5.\left(25-3\right)}=\frac{2^5.8}{2^5.22}=\frac{4}{11}\)
d) \(\frac{3^4.5-3^6}{3^4.13+3^4}=\frac{3^4.\left(5-3^2\right)}{3^4.\left(13+1\right)}=\frac{3^4.\left(5-9\right)}{3^4.14}=\frac{3^4.\left(-4\right)}{3^4.14}=\frac{-2}{7}\)
\(a,\left(-25\right).\left(75-45\right)-75.\left(45-25\right)\)
\(=\left(-25\right).20-75.20\)
\(=20.\left(-25-75\right)\)
\(=20.\left(-100\right)\)
\(=-2000\)
\(b,\frac{18.12-48.15}{-3.270-3.30}\)
\(=\frac{18.12-12.4.15}{-3.270-3.30}\)
\(=\frac{12.\left(18-60\right)}{-3.\left(270+30\right)}\)
\(=\frac{12.\left(-42\right)}{-3.300}\)
\(=\frac{14}{25}\)
\(c,\frac{2^5.7+2^5}{2^5.5^2-2^5.3}\)
\(=\frac{2^5.\left(7+1\right)}{2^5\left(25-3\right)}\)
\(=\frac{2^5.8}{2^5.22}\)
\(=\frac{8}{22}\)
\(=\frac{4}{11}\)
\(\dfrac{25.9-25.17}{-8.80-8.10}=\dfrac{-200}{-720}=\dfrac{5}{18}\)
\(\dfrac{48.12-48.15}{-3.270-3.30}=\dfrac{-144}{-900}=\dfrac{4}{25}\)
a, Quy đồng
\(\dfrac{5}{18}=\dfrac{5\times25}{18\times25}=\dfrac{125}{450}\)
\(\dfrac{4}{25}=\dfrac{4.18}{25.18}=\dfrac{72}{450}\)
ko cần làm thế đâu đề bài đâu phải là tính nhanh :))