【简答题】已知关于x,y的方程C:x 2 +y 2 -2x-4y+m=0. (1)若方程C表示圆,求m的取值范围; (2)若圆C与圆x 2 +y 2 -8x-12y+36=0外切,求m的值; (3)若圆C与直线l:x+2y-4=0相交于M,N两点,且 |MN|= 4 5 5 ,求m的值.
【单选题】全日制中学小学,除假期外,每周举行( )次升旗仪式
【简答题】A. Become more touchy-feely B. Eat more chocolate every day C. Eat less sodium and salt D. Eat potassium-rich foods
【单选题】女孩5岁,发热1个月、伴两下肢疼痛1周入院。卡介苗按时接种,否认结核接触史。体检:体温38.5℃,稍苍白,下肢有少许散在出血点,浅淋巴结易及,如绿豆及黄豆大,咽充血,心、肺无异常,腹软,肝肋下2cm,脾不肿大,两下肢无明显关节红肿,检查时稍感胀痛,神经系统无特殊。血红蛋白98s/L,白细胞数12×10/L,中性粒细胞0.30,淋巴细胞0.70,血沉48mm/h,骨髓穿刺证实为急性淋巴细胞白血病。假...
【单选题】已知圆C:(x-2) 2 +(y-1) 2 =25,过点M(-2,4)的圆C的切线l 1 与直线l 2 :ax+3y+2a=0平行,则l 1 与l 2 间的距离是( )
【单选题】过点M(-2,4)作圆C:(x-2) 2 +(y-1) 2 =25的切线l,且直线l 1 :ax+3y+2a=0与l平行,则l 1 与l间的距离是( )
【简答题】A. Become more touchy-feely B. Eat some chocolate every day C. Eat less sodium and salt D. Eat potassium-rich foods
【简答题】However life strikes you,cities worldwide have been growing even more rapidly.Some of this growth has occurred in the developed world,but the most dramatic increase has been in the Third World.A...