Tính, tính hợp lí:
(-5).11.(-2)^3
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\(\dfrac{2}{7}-\dfrac{3}{11}+\dfrac{5}{7}-\dfrac{8}{11}\\ =\left(\dfrac{2}{7}+\dfrac{5}{7}\right)-\left(\dfrac{3}{11}+\dfrac{8}{11}\right)\\ =\dfrac{7}{7}-\dfrac{11}{11}\\ =1-1\\ =0\)
(2/5 + 2/7 - 2/11) : (3/7 - 3/11 + 3/5)
= 194/385 : 291/385
= 194/385 . 385/291
= 2/3
\(#N\)
\(-\dfrac{11}{7}+\dfrac{13}{-2}+-\dfrac{6}{17}=-\dfrac{113}{14}+-\dfrac{6}{17}=-\dfrac{2005}{238}\)
\(\dfrac{13}{-8}+-\dfrac{7}{20}+\dfrac{3}{-8}=\left(-\dfrac{13}{8}+-\dfrac{3}{8}\right)+-\dfrac{7}{20}=-2+-\dfrac{7}{20}=-\dfrac{47}{20}\)
\(-\dfrac{4}{7}+\dfrac{11}{5}+\dfrac{1}{5}+-\dfrac{7}{3}=-\dfrac{4}{7}+\left(\dfrac{11}{5}+\dfrac{1}{5}\right)+-\dfrac{7}{3}=-\dfrac{4}{7}+\dfrac{12}{5}+-\dfrac{7}{3}=-\dfrac{53}{105}\)
\(\dfrac{38}{11}+\left(\dfrac{16}{13}+\dfrac{6}{11}\right)\\ =\dfrac{38}{11}+\dfrac{16}{13}+\dfrac{6}{11}\\ =\left(\dfrac{38}{11}+\dfrac{6}{11}\right)+\dfrac{16}{13}\\ =\dfrac{44}{11}+\dfrac{16}{13}\\ =4+\dfrac{16}{13}\\ =\dfrac{52}{13}+\dfrac{16}{13}\\ =\dfrac{68}{13}\\ \dfrac{3}{4}:\dfrac{3}{5}-\dfrac{1}{5}\\ =\dfrac{3}{4}\times\dfrac{5}{3}-\dfrac{1}{5}\\ =\dfrac{5}{4}-\dfrac{1}{5}\\ =\dfrac{25-4}{20}\\ =\dfrac{21}{20}\)
Phép tính 1:
\(\dfrac{38}{11}+\left(\dfrac{16}{13}+\dfrac{6}{11}\right)\)
\(=\left(\dfrac{38}{11}+\dfrac{6}{11}\right)+\dfrac{16}{13}\)
\(=4+\dfrac{16}{13}=\dfrac{4\cdot13+16}{13}\)(Dấu "." trong phép tính là dấu nhân)
\(=\dfrac{68}{13}\)
Phép tính 2:
\(\dfrac{3}{4}:\dfrac{3}{5}-\dfrac{1}{5}\)
\(=\dfrac{3}{4}\cdot\dfrac{5}{3}-\dfrac{1}{5}\)
\(=\dfrac{\left(3\cdot5\right):3\cdot5}{\left(4\cdot3\right):3\cdot5}-\dfrac{1\cdot4}{5\cdot4}\)
\(=\dfrac{25}{20}-\dfrac{4}{20}\)
\(=\dfrac{21}{20}\)
trả lời:
B = 7x( 5/2x7 + 4/7x11 + 3/11x14 + 1/14x15 + 13/15x28 )
B = 7x(1/2 - 1/7 + 1/7 - 1/11 +....+ 1/15 - 1/28)
B = 7x(1/2 - 1/28)
B = 7x13/28
B = 13/4
Bàì làm:
\(B=\frac{5}{2.1}+\frac{4}{1.11}+\frac{3}{11.2}+\frac{1}{2.15}+\frac{13}{15.4}\)
\(B=7.\left(\frac{5}{2.7}+\frac{4}{7.11}+\frac{3}{11.14}+\frac{1}{14.15}+\frac{13}{15.28}\right)\)
\(B=7.\left(\frac{1}{2}-\frac{1}{7}+\frac{1}{7}-\frac{1}{11}+\frac{1}{11}-\frac{1}{14}+\frac{1}{14}-\frac{1}{15}+\frac{1}{15}-\frac{1}{28}\right)\)
\(B=7.\left(\frac{1}{2}-\frac{1}{28}\right)\)
\(B=7.\frac{13}{28}\)
\(B=\frac{13}{4}\)
b)
\(=\frac{3}{7}\left(\frac{9}{11}+\frac{2}{11}\right)\)
\(=\frac{3}{7}.1=\frac{3}{7}\)
Trả lời :
\(a,4.\left\{3^2.\left[\left(5^2+2^3\right):11\right]-26\right\}+2002\)
\(=4.\left\{9.\left[\left(25+8\right):11\right]-26\right\}+2002\)
\(=4.\left\{9.\left[33:11\right]-26\right\}+2002\)
\(=4.\left\{9.3-26\right\}+2002\)
\(=4.1+2002\)
\(=2006\)
Hok_tốt
#Thiên_Hy
\(4.\left\{3^2.\left[\left(5^2+2^3\right):11\right]-26\right\}+2002\)
\(=4.\left\{9.\left[\left(25+8\right):11\right]-26\right\}+2002\)
\(=4.\left\{9.\left[33:11\right]-26\right\}+2002\)
\(=4.\left\{9.3-26\right\}+2002\)
\(=4.\left\{27-26\right\}+2002\)
\(=4.1+2002\)
\(=4+2002\)
\(=2006\)
~ Hok tốt ~
(-5) . 11 . (-2)^3
= (-5) . 11 . (-8)
= [(-5) . (-8)] . 11
= 40 . 11
= 440
(-5) . 11 . (-2)^3
= (-5) . 11 . (-8)
= (-5). (-8) . 11
= 5 . 8 . 11
= 40 . 11
= 440
nếu đúng thì các bn tk cho mk nhé