Giúp em câu này và chỉ ra phương pháp giải với ạ.
B=5.8^12.9^5.(-3)^2.(-16)^5
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7.49^3.81^5.(-7)^10.(-8)^5
C=13.4^7.9^15-9^7.(-16)^4
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15.3^12.2^8+3.27^5.(-8)^10
K
Khách
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Những câu hỏi liên quan
8 tháng 4 2023
1)\(\dfrac{2}{9}+\dfrac{-3}{4}+\dfrac{5}{30}\)
\(=\dfrac{2.20}{9.20}+\dfrac{-3.45}{4.45}+\dfrac{5.6}{30.6}\)
\(=\dfrac{40}{180}+\dfrac{-135}{180}+\dfrac{30}{180}\)
\(=\dfrac{40+\left(-135\right)+30}{180}\)
\(=\dfrac{-65}{180}\)
\(=\dfrac{-13}{36}\)
2)\(\dfrac{-7}{12}-\dfrac{11}{18}\)
\(=\dfrac{-7.3}{12.3}-\dfrac{11.2}{18.2}\)
\(=\dfrac{-21}{36}-\dfrac{22}{36}\)
\(=\dfrac{-21-22}{36}\)
\(=\dfrac{-43}{36}\)
3)\(\dfrac{7}{8}-\dfrac{-5}{16}\)
\(=\dfrac{7.2}{8.2}-\dfrac{-5}{16}\)
\(=\dfrac{14}{16}-\dfrac{-5}{16}\)
\(=\dfrac{14-\left(-5\right)}{16}\)
\(=\dfrac{19}{16}\)
4)\(\dfrac{3}{8}-\dfrac{-9}{10}-\dfrac{5}{16}\)
\(=\dfrac{3.10}{8.10}-\dfrac{-9.8}{10.8}-\dfrac{5.5}{16.5}\)
\(=\dfrac{30}{80}-\dfrac{-72}{80}-\dfrac{25}{80}\)
\(=\dfrac{30-\left(-72\right)-25}{80}\)
\(=\dfrac{77}{80}\)
C
20 tháng 4 2022
\(\dfrac{7}{5}+\dfrac{4}{7}-\dfrac{9}{10}=\dfrac{49-20}{35}-\dfrac{9}{10}=\dfrac{19}{35}-\dfrac{9}{10}=\dfrac{190-315}{350}=\dfrac{-125}{350}\)
\(\dfrac{2}{1}+\dfrac{3}{4}\text{×}\dfrac{8}{5}=\dfrac{8+3}{4}\text{×}\dfrac{8}{5}=\dfrac{11\text{×}8}{4\text{×}5}=\dfrac{88}{20}\)
mấy câu kia áp dụng là dc!
29 tháng 1
a: \(\dfrac{5}{3}\cdot\dfrac{7}{10}=\dfrac{5}{10}\cdot\dfrac{7}{3}=\dfrac{14}{3}>2\)
\(\dfrac{5}{7}:\dfrac{7}{10}=\dfrac{5}{7}\cdot\dfrac{10}{7}=\dfrac{50}{49}< 2\)
=>\(\dfrac{5}{3}\cdot\dfrac{7}{10}>\dfrac{5}{7}:\dfrac{7}{10}\)
b: \(\dfrac{4}{5}\cdot\dfrac{5}{6}=\dfrac{4}{6}=\dfrac{2}{3}\)
\(\dfrac{8}{9}:\dfrac{4}{3}=\dfrac{8}{9}\cdot\dfrac{3}{4}=\dfrac{8}{4}\cdot\dfrac{3}{9}=\dfrac{2}{3}\)
Do đó: \(\dfrac{4}{5}\cdot\dfrac{5}{6}=\dfrac{8}{9}:\dfrac{4}{3}\)
c: \(\dfrac{5}{11}\cdot\dfrac{33}{15}=\dfrac{5}{15}\cdot\dfrac{33}{11}=\dfrac{3}{3}=1\)
\(\dfrac{6}{17}\cdot\dfrac{34}{25}=\dfrac{34}{17}\cdot\dfrac{6}{25}=2\cdot\dfrac{6}{25}=\dfrac{12}{25}< 1\)
=>\(\dfrac{5}{11}\cdot\dfrac{33}{15}>\dfrac{6}{17}\cdot\dfrac{34}{25}\)
d: \(\dfrac{15}{19}\cdot\dfrac{38}{5}=\dfrac{15}{5}\cdot\dfrac{38}{19}=3\cdot2=6\)
\(\dfrac{15}{16}:\dfrac{3}{8}=\dfrac{15}{16}\cdot\dfrac{8}{3}=\dfrac{15}{3}\cdot\dfrac{8}{16}=\dfrac{5}{2}\)<6
=>\(\dfrac{15}{19}\cdot\dfrac{38}{5}>\dfrac{15}{16}:\dfrac{3}{8}\)
18 tháng 7 2023
1) \(3^x=\dfrac{9^8}{27^3\cdot81^2}\)
\(\Rightarrow3^x=\dfrac{\left(3^2\right)^8}{\left(3^3\right)^3\cdot\left(3^4\right)^2}\)
\(\Rightarrow3^x=\dfrac{3^{16}}{3^{15}}\)
\(\Rightarrow3^x=3\)
\(\Rightarrow x=1\)
2) \(\dfrac{2^{4-x}}{16^5}=32^6\)
\(\Rightarrow\dfrac{2^{4-x}}{\left(2^4\right)^5}=\left(2^5\right)^6\)
\(\Rightarrow\dfrac{2^{4-x}}{2^{20}}=2^{30}\)
\(\Rightarrow2^{4-x}=2^{20}\cdot2^{30}\)
\(\Rightarrow2^{4-x}=2^{50}\)
\(\Rightarrow4-x=50\)
\(\Rightarrow x=-46\)
3) \(\dfrac{2^{2x-3}}{4^{10}}=8^3\cdot16^5\)
\(\Rightarrow\dfrac{2^{2x-3}}{\left(2^2\right)^{10}}=\left(2^3\right)^3\cdot\left(2^4\right)^5\)
\(\Rightarrow\dfrac{2^{2x-3}}{2^{20}}=2^{29}\)
\(\Rightarrow2^{2x-3}=2^{49}\)
\(\Rightarrow2x-3=49\)
\(\Rightarrow2x=52\)
\(\Rightarrow x=26\)
KV
4 tháng 12 2023
a) 1/2 + 3/4 - (3/4 - 4 - 5)
= 1/2 + 3/4 - 3/4 + 4 + 5
= (3/4 - 3/4) + (4 + 5) + 1/2
= 0 + 9 + 1/2
= 19/2
b) [9/16 + 8/(-27)] - (19/27- 7/16 - 2)
= 9/16 - 8/27 - 19/27 + 7/16 + 2
= (9/16 + 7/16) + (-8/27 - 19/27) + 2
= 1 - 1 + 2
= 2
c) -5/8 . [4/9 + 7/(-12)]
= -5/8 . (-5/36)
= 25/288
d) 7/10 . (-3/5) + 7/10 . (-2/5) - (-3/10)
= 7/10 . (-3/5 - 2/5) + 3/10
= 7/10 . (-1) + 3/10
= -2/5
e) -3/7 . 5/9 + 4/9 . (-3/7) + 2 3/7
= -3/7 . (5/9 + 4/9) + 17/7
= -3/7 . 1 + 17/7
= 2
f) 8 2/7 - (3 4/9 + 4 2/7)
= 8 + 2/7 - 3 - 4/9 - 4 - 2/7
= (8 - 3 - 4) + (2/7 - 2/7) - 4/9
= 1 - 4/9
= 5/9
h) 3.(-1/2)² - (4/5 + 8/15) : 5/6
= 3.1/4 - 4/3 : 5/6
= 3/4 - 8/5
= -17/20
S
10 tháng 4 2019
a) (- 25) x 125,4 x (-8) x (-17)
= (- 25 x 4) x (- 8 x 125) x (-17)
= (-100) x (-1000) x (-17)
= - 1 700 000
b) \(\frac{-3}{4}+\frac{2}{7}+\frac{-1}{4}+\frac{3}{5}+\frac{5}{7}\)
\(=\left(\frac{-3}{4}+\frac{-1}{4}\right)+\left(\frac{2}{7}+\frac{5}{7}\right)+\frac{3}{5}\)
\(=-1+1+\frac{3}{5}\)
\(=0+\frac{3}{5}=\frac{3}{5}\)
c) \(\frac{7}{19}.\frac{8}{11}+\frac{7}{19}.\frac{3}{11}-\frac{12}{19}\)
\(=\frac{7}{19}.\left(\frac{8}{11}+\frac{3}{11}\right)-\frac{12}{19}\)
\(=\frac{7}{19}.1-\frac{12}{19}\)
\(=\frac{7}{19}-\frac{12}{19}=\frac{-5}{19}\)
d) \(19\frac{5}{8}:\frac{7}{2013}-26\frac{5}{8}:\frac{7}{2013}\)
\(=\left(19\frac{5}{8}-26\frac{5}{8}\right):\frac{7}{2013}\)
\(=-7:\frac{7}{2013}\)
\(=-2013\)
e) \(\frac{-5}{12}.\frac{2}{11}+\frac{-5}{12}.\frac{9}{11}+\frac{5}{12}\)
\(=\frac{-5}{12}.\left(\frac{2}{11}+\frac{9}{11}\right)+\frac{5}{12}\)
\(=\frac{-5}{12}.1+\frac{5}{12}\)
\(=\frac{-5}{12}+\frac{5}{12}=0\)
~Học tốt~
KV
30 tháng 10 2023
Câu 9
a) 2/15 + (-3/5)
= 2/15 - 3/5
= 2/15 - 9/15
= -7/15
b) -5/7 + 3/7 . (-2/9)
= -5/7 - 2/21
= -15/21 - 2/21
= -17/21
c) 5/16 - (7/15 - 3/16) + 17/30
= 5/16 - 7/15 + 3/16 + 17/30
= (5/16 + 3/16) + (17/30 - 14/30)
= 1/2 + 1/10
= 5/10 + 1/10
= 6/10
= 3/5
NM
30 tháng 10 2023
\(a,\dfrac{2}{15}+\left(-\dfrac{3}{5}\right)\\ =\dfrac{2}{15}-\dfrac{3}{5}\\ =\dfrac{2}{15}-\dfrac{9}{15}\\ =-\dfrac{7}{15}\\ b,-\dfrac{5}{7}+\dfrac{3}{7}\times\left(-\dfrac{2}{9}\right)\\ =-\dfrac{5}{7}-\dfrac{2}{21}\\ =-\dfrac{15}{21}-\dfrac{2}{21}\\ =-\dfrac{17}{21}\\ c,\dfrac{5}{16}-\left(\dfrac{7}{15}-\dfrac{3}{16}\right)+\dfrac{17}{30}\\ =\dfrac{5}{16}-\dfrac{7}{15}+\dfrac{3}{16}+\dfrac{17}{30}\\ =\left(\dfrac{5}{16}+\dfrac{3}{16}\right)-\left(\dfrac{17}{15}+\dfrac{17}{30}\right)\\ =\dfrac{1}{2}-\dfrac{17}{10}\\ =\dfrac{5}{10}-\dfrac{17}{10}\\ =-\dfrac{6}{5}.\)
14 tháng 6 2023
a: =7/8:(2/9-18+1/36)-5/12
=-7/142-5/12=-397/852
b: =3/7(4/9+5/9:6/12)=2/3
c: =5^8(16/31-47/31)+1/3=-5^8+1/3
d: =7/2(3/8+5/8:4/15)=609/64
