已知数列an为等差数列,an=n,则a1*a2-a2*a3+a3*a4-a4*a5+...-a100*a101=

问题描述:

已知数列an为等差数列,an=n,则a1*a2-a2*a3+a3*a4-a4*a5+...-a100*a101=

a1*a2-a2*a3+a3*a4-a4*a5+...-a100*a101==1×2-2×3+3×4-4×5+..-100×101=2×(1-3)+4×(3-5)+..+100×(99-101)=-2×(2+4+6+..+100)=-2×(2+100)×50÷2=-5100明教为您解答,请点击[满意答案];如若您有不满意之处,请...