计算:(5+2)+(5+2×2)+(5+2×3)+.+(5+2×90).

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计算:(5+2)+(5+2×2)+(5+2×3)+.+(5+2×90).计算:(5+2)+(5+2×2)+(5+2×3)+.+(5+2×90).计算:(5+2)+(5+2×2)+(5+2×3)+.+(

计算:(5+2)+(5+2×2)+(5+2×3)+.+(5+2×90).
计算:(5+2)+(5+2×2)+(5+2×3)+.+(5+2×90).

计算:(5+2)+(5+2×2)+(5+2×3)+.+(5+2×90).
原式=5*90+2*(1+2+……+90)=450+90*91=8640