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\(A=\frac{\left[\left(25-1\right):1+1\right]\left(25+1\right)}{2}=325.\)
\(B=\frac{\left[\left(51-3\right):2+1\right]\left(51+3\right)}{2}=675\)
\(C=\frac{\left[\left(81-1\right):4+1\right]\left(81+1\right)}{2}=861\)
a: =-5/9-4/9+8/15+7/15-2/11=-2/11
b: =10/17+7/17-5/13-8/13+11/25
=11/25
c: =(9/12-2/12)*3/2=7/12*3/2=21/24=7/8
d: =(31/10-25/10)*3-2
=3/5*3-2
=9/5-2
=-1/5
a, \(\dfrac{5}{9}.\dfrac{10}{11}+\dfrac{5}{9}.\dfrac{14}{11}-\dfrac{5}{9}.\dfrac{15}{11}=\dfrac{5}{9}.\left(\dfrac{10}{11}+\dfrac{14}{11}-\dfrac{15}{11}\right)=\dfrac{5}{9}.\dfrac{9}{11}=\dfrac{5}{11}\)
b, \(\dfrac{6}{7}.\dfrac{8}{13}+\dfrac{6}{13}.\dfrac{9}{7}-\dfrac{3}{13}.\dfrac{6}{7}\)\(=\dfrac{6}{7}.\left(\dfrac{8}{13}-\dfrac{3}{13}\right)+\dfrac{6}{13}.\dfrac{9}{7}=\dfrac{6}{7}.\dfrac{5}{13}+\dfrac{54}{91}=\dfrac{30}{91}+\dfrac{54}{91}=\dfrac{84}{91}=\dfrac{12}{13}\)
Bạn ơi, gõ latex cho dễ nhìn nhé!
...=-15-9=-24
...=4+7=11
...=-12-13=-25
...=13+10=23
...=-4-7=-11
...=-9+13=4
...=12+0=12
...=0-7=-7
...=0+3=3
...=15-17=-2
...=-6
...=-23
...=15-15=0
a) B = \(\dfrac{4}{3}.\dfrac{5}{4}....\dfrac{21}{20}=\dfrac{1}{3}.1.....\dfrac{21}{1}=\dfrac{21}{3}=7\)
b) Em chịu, chưa học số âm :)
a)-4/11+5/6+7/11-5/6
b)-5/6.7/13+19/13.6/-5+2/5
c)3/7.(-0,5+3/2)-2/7:25%
mọi người giúp e vs ạ
e cần gấp
a; - \(\dfrac{4}{11}\) + \(\dfrac{5}{6}\) + \(\dfrac{7}{11}\) - \(\dfrac{5}{6}\)
= (-\(\dfrac{4}{11}\) + \(\dfrac{7}{11}\)) + (\(\dfrac{5}{6}\) - \(\dfrac{5}{6}\))
= - \(\dfrac{3}{11}\) + 0
= - \(\dfrac{3}{11}\)
b; -\(\dfrac{5}{6}\).\(\dfrac{7}{13}\) + \(\dfrac{19}{13}\).\(\dfrac{6}{-5}\) + \(\dfrac{2}{5}\)
= - \(\dfrac{35}{78}\) - \(\dfrac{114}{65}\) + \(\dfrac{2}{5}\)
= - \(\dfrac{859}{390}\) + \(\dfrac{2}{5}\)
= - \(\dfrac{703}{390}\)
a,
A=1−3−5−7−9−...−97−99a)A=1−3−5−7−9−...−97−99
=1−(3+5+7+...+99)=1−(3+5+7+...+99)
=1−(99+3).[(99−3):2+1]2=1−(99+3).[(99−3):2+1]2
=1−2499=−2498=1−2499=−2498
b)B=1+3−5−7+9+...+97−99b)B=1+3−5−7+9+...+97−99
=(−8)+(−8)+(−8)+...+(−8)+97−99=(−8)+(−8)+(−8)+...+(−8)+97−99
=(−8).12+(−2)=−98=(−8).12+(−2)=−98
c)C=1−3−5+7+9−11−13+15+...+97−99c)C=1−3−5+7+9−11−13+15+...+97−99
=0+0+0+0+0+...+0−99=0+0+0+0+0+...+0−99
=−99
a) 5/17 * 8/-7+8/17*-7/3+-7/3*4/17
-40/119 + 12/17 × -7/3
-40/119 + -28/17 =-236/119
b) -10/13 + 5/17 - 3/13 + 12/17 - 11/20
(5/17+12/17)-(10/13+3/13)-11/20
-11/20
a) 5/17 * 8/-7+8/17*-7/3+-7/3*4/17
-40/119 + 12/17 × -7/3
-40/119 + -28/17 =-236/119
b) -10/13 + 5/17 - 3/13 + 12/17 - 11/20
(5/17+12/17)-(10/13+3/13)-11/20
-11/20
\(4\times5^3-6\times3^2\)
\(=4\times125-6\times9\)
\(=500-54\)
\(=446\)
\(\left[4^2+\left(15-3^2\right)^2\right]\div13\)
\(=\left[16+\left(15-9\right)^2\right]\div13\)
\(=\left[16+6^2\right]\div13\)
\(=\left(16+36\right)\div13\)
\(=52\div13\)
\(=4\)