如图的直径,弦于点E,,⊙O的半径为,则弦的长为____________
计算:_____________;
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计算:x3· x —3 = ______;a 6÷a2·a3 =___________;2 0 + 2—1 =___ ___.
找规律填空: ……
若a+b="5," ab=6,则a2+b2=________