tính theo cách hợp lí :
25/3 + 0.25 + 1/2 - ( 3.5 + 5/2 - 3/4 )
Những câu hỏi liên quan
Tính bằng cách hợp lí : 0.25 + 25% x 55 + 1/4 x 45 - 2/8
\(0,25+25\%\times55+\dfrac{1}{4}\times45-\dfrac{2}{8}\)
\(=\dfrac{1}{4}+\dfrac{1}{4}\times55+\dfrac{1}{4}\times45-\dfrac{1}{4}\)
\(=\dfrac{1}{4}\times\left(1+55+45-1\right)\)
\(=\dfrac{1}{4}\times100\)
\(=25\)
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\(0,25+25\%\times55+\dfrac{1}{4}\times45-\dfrac{2}{8}\)
\(=\dfrac{1}{4}+\dfrac{1}{4}\times55+\dfrac{1}{4}\times45-\dfrac{1}{4}\)
\(=\dfrac{1}{4}\times1+\dfrac{1}{4}\times55+\dfrac{1}{4}\times45-\dfrac{1}{4}\times1\)
\(=\dfrac{1}{4}+\left(1+55+45-1\right)\)
\(=\dfrac{1}{4}\times100\)
\(=0,25\times100\)
\(=25\)
\(#:)\)
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tính bằng cách hợp lí {nếu có thể}
A=2/5+ -4/3 + {-1/2}
B=1/3-[{-5/4}-{1/4+3/8}]
C=15 1/4:{-5/7-25 1/4:{-5/7}
1. Tính hợp lí : A. (0.25)^3×32
B. (-0.125)^3.80^4
C. 8^2×4^5/2^20
D. 81^11×3^17/27^10×9^15
tính theo cách hợp lí
a) \(\frac{3}{1.3}+\frac{3}{3.5}+.....+\frac{3}{49.51}\)
b) \(\frac{1}{2}-\frac{1}{2016.2015}-\frac{1}{2015.2014}-....-\frac{1}{3.2}\)
Tính hợp lí nếu có thể
a)1/2.(2/9+3/7-5/27)
b)1/2+3/4-(3/4-4/5)
c)1/3.5/7-7/27.36/14
\(\frac{1}{2}\cdot\left(\frac{2}{9}+\frac{3}{7}-\frac{5}{27}\right)=\frac{1}{2}\cdot\left(\frac{6}{27}-\frac{5}{27}+\frac{3}{7}\right)=\frac{1}{2}\cdot\frac{3}{7}+\frac{1}{2}\cdot\frac{1}{27}=\frac{3}{14}+\frac{1}{54}=\frac{44}{189}\)
\(\frac{1}{2}+\frac{3}{4}-\left(\frac{3}{4}-\frac{4}{5}\right)=\frac{1}{2}+\frac{3}{4}-\frac{3}{4}+\frac{4}{5}=\frac{1}{2}+\frac{4}{5}=\frac{13}{10}\)
\(\frac{1}{3}\cdot\frac{5}{7}-\frac{7}{27}\cdot\frac{36}{14}=\frac{1}{3}\cdot\frac{5}{7}-\frac{7}{27}\cdot\frac{18}{7}=\frac{1}{3}\cdot\frac{5}{7}-\frac{6}{7}=\frac{5}{21}-\frac{14}{21}=\frac{-3}{7}\)
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s=3/4-0.25-[7/3+(-9/2)]-5/6
Đề là tính băng cách hợp lí
giúp mik nha!
thank you các bạn nhìu
\(S=\frac{3}{4}-0,25-\left[\frac{7}{3}+\left(\frac{-9}{2}\right)\right]-\frac{5}{6}\)
\(\Rightarrow S=\frac{3}{4}-\frac{1}{4}-\left(\frac{7}{3}-\frac{9}{2}\right)-\frac{5}{6}\)
\(\Rightarrow S=\frac{1}{2}-\frac{7}{3}+\frac{9}{2}-\frac{5}{6}\)
\(\Rightarrow S=\frac{3}{6}-\frac{14}{6}+\frac{27}{6}-\frac{5}{6}\)
\(\Rightarrow S=\frac{11}{6}\)
Tính theo cách hợp lí
(1-5/17).(3/8-5^2/24)
\(\left(1-\dfrac{5}{17}\right)\left(\dfrac{3}{8}-\dfrac{5^2}{24}\right)\)
\(=\dfrac{17-5}{17}\cdot\dfrac{9-25}{24}\)
\(=\dfrac{12}{17}\cdot\dfrac{-16}{24}=\dfrac{-16}{17}\cdot\dfrac{12}{24}=\dfrac{-16}{17}\cdot\dfrac{1}{2}=-\dfrac{8}{17}\)
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Tính một cách hợp lí: \(\dfrac{4^2.25^2+32.125}{2^3.5^2}\)
\(\dfrac{4^2.25^2+32.125}{2^3.5^2}\)
\(=\dfrac{\left(2^2\right)^2.\left(5^2\right)^2+2^5.5^3}{2^3.5^2}\)
\(=\dfrac{2^4.5^4+2^5.5^3}{2^3.5^2}\)
\(=\dfrac{2^3.5^2\left(2.5^2+2^2.5\right)}{2^3.5^2}\)
\(=2.5^2+2^2.5\)
\(=2.25+4.5=50+20=70\)
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Tính bằng cách hợp lí:
a) (9/25 - 2 . 18 ) / (19/5 + 0,2 )
b) 12 . (-2/3)^2 + 4/3
a) \(=\frac{\left(\frac{9}{25}-36\right)}{\frac{19}{5}+\frac{1}{5}}=\frac{\frac{9}{25}-\frac{900}{25}}{\frac{20}{5}}=\frac{-891}{25}:4\)\(=\frac{-891}{25\cdot4}=\frac{-891}{100}=-8,91\)
b) \(=12\cdot\frac{\left(-2\right)^2}{3^2}+\frac{4}{3}=12\cdot\frac{4}{9}+\frac{4}{3}\)\(=\frac{48}{9}+\frac{4}{3}=\frac{48}{9}+\frac{12}{9}=\frac{60}{9}\)
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