Toán Lớp 6: Tính nhanh:
A=1-2+3-4+…+99-100
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Toán Lớp 6: Tính nhanh:
A=1-2+3-4+…+99-100
Comments ( 2 )
A=(1-2)+(3-4)+…+(99-100)
A=\underbrace{(-1)+(-1)+…+(-1)}_{50 số (-1)}
=>A=50.(-1)
=>A=-50
Vậy A=-50