Tính tổng: A = 1 - 2019^1 + 2019^2 - 2019^3 +............+ 2019^2018 - 2019^2019
Bài 1.tìm x
1) (x+2)+(4x+4)+(7x+6)+..........+(25x+18)+(28x+20)=1560
2) (x+1)+(x+2)+(x+3)+...............+(x+100)=5750
3) (x-1)+(x-2)+(x-3)+.....................+(x-100)=100
4) (2x-1)+(4x-2)+.............................+(400x-200)=5+10+............+1000
Bài 2.Tính
A=1-2019^1+2019^2-2019^3+............+2019^2018-2019^2019
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