等差数列中,a4+a6+a8+a10+a12=240,则a9-(1/3)*a11=?

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等差数列中,a4+a6+a8+a10+a12=240,则a9-(1/3)*a11=?
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等差数列中,a4+a6+a8+a10+a12=240,则a9-(1/3)*a11=?
等差数列中,a4+a6+a8+a10+a12=240,则a9-(1/3)*a11=?

等差数列中,a4+a6+a8+a10+a12=240,则a9-(1/3)*a11=?
a4+a6+a8+a10+a12=240
5a1+35d=240
a1+7d=48
则a9-(1/3)*a11
=a1+8d-1/3(a1+10d)
=2/3a1+14/3d
=2/3(a1+7d)
=2/3*48
=32