赞 bluesky9898 幼苗
共回答了12个问题采纳率：100% 举报
sin^6α +cos^6α=(sin^2α+cos^2α)(sin^4α-sin^2αcos^2α+cos^4α)=sin^4α-sin^2αcos^2α+cos^4α
2(sin^6 α +cos^6α)-3(sin^4α+cos^4α)=2sin^4α-2sin^2αcos^2α+2cos^4α-3sin^4α-3cos^4α
=-sin^4α-cos^4α-2sin^2αcos^2α=-(sin^2α+cos^2α)^2=-1
2(sin^6 α +cos^6α)-3(sin^4α+cos^4α)=2sin^4α-2sin^2αcos^2α+2cos^4α-3sin^4α-3cos^4α
=-sin^4α-cos^4α-2sin^2αcos^2α=-(sin^2α+cos^2α)^2=-1
1年前
9
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你能帮帮他们吗