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a) A = 1 + ( - 2 ) + 3 + ... + ( - 98 ) + 99
A = 1 + [ ( - 2 ) + 3 ] + ... + [ ( - 98 ) + 99 ]
A = 1 + 1 + ... + 1
A = 1 . 50
A = 50
miucool:
A = 1 + (-2) + 3 + ... + (-98) + 99
A = 1 + [(-2) + 3)] + ... + [(-98) + 99)]
A = 1 + 1 + ... + 1
Có 50 cặp số:
A = 1 . 50
A = 50
Vậy A =50
(^_^)
a, (- 40 - 16 + 32 ) + ( 40 + 116 - 32 )
=( - 40 )- 16 + 32 + 40 + 116 - 32
=[(-40)+40]+32-32+116-16
=0+ (32-32)+(116-16)
=0+0+100
=100
b, -15 + 5 + ( 20 - 100 - 2017 ) - ( - 15 - 2017 )
= -15 + 5 + 20 - 100 - 2017 + 15 + 2017
=[(-15 )+ 15] + (2017 - 2017 ) + 20-100
=0+0+(20-100)
= - 80
a) \(5\dfrac{3}{8}-1\dfrac{9}{10}=\dfrac{43}{8}-\dfrac{19}{10}=\dfrac{215}{40}-\dfrac{76}{40}=\dfrac{139}{40}\)
b) \(\left(-3\dfrac{1}{4}\right)+\left(-2\dfrac{1}{3}\right)=-\dfrac{13}{4}+\left(-\dfrac{7}{3}\right)=-\dfrac{39}{12}+\left(-\dfrac{28}{12}\right)=\dfrac{-67}{12}\)
c) \(\left(-5\dfrac{1}{8}\right)+3\dfrac{2}{4}=\left(-\dfrac{41}{8}\right)+\dfrac{14}{4}=\left(-\dfrac{41}{8}\right)+\dfrac{28}{8}=-\dfrac{13}{8}\)
d)\(\left(-3\right)-\left(-2\dfrac{2}{5}\right)=\left(-3\right)-\left(-\dfrac{12}{5}\right)=\left(-\dfrac{15}{5}\right)+\left(-\dfrac{12}{5}\right)=-\dfrac{27}{5}\)
a)(1/4+3/4)-(5/13+8/13)+2/11=1-1+2/11=2/11
b)(21/31+10/31)-16/7+(44/53+9/53)=1+1-16/7=14/7-16/7=-2/7