13.设 (2x+1)=(x)^4, 则 '(x)= __

例3 设椭圆 :dfrac ({x)^2}({a)^2}+dfrac ({y)^2}({b)^2}=1(agt bgt 0) 的左、-|||-右焦点分别为F1,F2,P是椭圆C上的点,-|||-(F)_(2)bot (F)_(1)(F)_(2) angle P(F)_(1)(F)_(2)=(30)^circ ,则椭圆C的离-|||-心率为 __ .-|||-延伸探究1 若将本例中" (F)_(2)bot (F)_(1)(F)_(2),-|||-angle P(F)_(1)(F)_(2)=(30)^circ "改为" angle P(F)_(2)(F)_(1)=(75)^circ angle P(F)_(1)(F)_(2)-|||-=(45)^circ ,求椭圆C的离心率.

一天泉弟子携带若干件珠宝，前往灾后不羡仙兼济天下。若每户赠与3件珠宝，则还余1；若每户赠与5件珠宝，则还余2；若每户赠与7件珠宝，则还余1。则此弟子出门至少随身携带了多少件珠宝？

某玩具厂把630件玩具分别装在5个塑料箱和6个纸箱里.1个塑料箱与3个纸箱装的玩具同样多，每个塑料箱和每个纸箱各装多少件玩具？

双曲线C的两个焦点为F1，F2，以C的实轴为直径的圆记为D，过F1作D的切线与C交于M，N两点，且cos∠F1NF2=(3)/(5)，则C的离心率为（　　）A. ((sqrt(5)))/(2)B. (3)/(2)C. ((sqrt(13)))/(2)D. ((sqrt(17)))/(2)

23.设二元函数 =xln (xy), 计算 dfrac ({partial )^2z}(partial {x)^2},dfrac ({partial )^2z}(partial {y)^2},dfrac ({partial )^2z}(partial xpartial y),dfrac ({partial )^2z}(partial xpartial y))(a,1)

在下列四个图中,G,N,M,H分别是正三棱柱的顶点或所在棱的中点,-|||-则表示直线GH,MN是异面直线的图形有 __ (填序号)-|||-G G M G M G M-|||-H-|||-N-|||-M `N:-|||-N H H N H-|||-① ② ③ ④

((2-x))^10=(a)_(0)+(a)_(1)x+((2-x))^10=(a)_(0)+(a)_(1)x+，则((2-x))^10=(a)_(0)+(a)_(1)x+（ ）。 A: ((2-x))^10=(a)_(0)+(a)_(1)x+ B: ((2-x))^10=(a)_(0)+(a)_(1)x+ C: ((2-x))^10=(a)_(0)+(a)_(1)x+ D: ((2-x))^10=(a)_(0)+(a)_(1)x+

__ 姓括 成绩-|||-times 34=-|||--|||-x 3.4-|||-times 28=-|||-24-|||-X 2.8-|||-times 35=93 2-|||--|||-X 3.5-|||-27×42=-|||-27-|||-A.4.2-|||-times 58=-|||--|||-(S)_(2)8-|||-times 76=-|||-4 2-|||-times 73-|||-times 57=-|||-5.7-|||-3 4-|||-times 64=-|||-3 6-|||-times 64-|||-times 72=-|||-7 5-|||-times 83=-|||-9 3-|||-X 8 3-|||-times 96=-|||-5 6-|||-times 9.6-|||-times 52=-|||-48-|||-X 5 2-|||-times 42=-|||--|||-.2-|||-times 23=-|||-65-|||-times 23-|||-74×34=-|||--|||-times 34-|||-times 85=-|||-6 5-|||-times 85-|||-times 37=-|||--|||-times 37-|||-times 96=-|||-2 4-|||-X 9.6-|||-times 89=-|||-3 4-|||-times 819-|||-times 58=-|||--|||--|||-times 29=-|||-3 2-|||-X 2.9-|||-times 58=-|||-5 4-|||-X 5.8-|||-times 26=-|||-9 2-|||-X 2.6-|||-times 53=-|||-3 2-|||-times 53-|||-times 94=-|||-6 7-|||-times 9=4

例4 设随机变量X的概率密度为-|||-f(x)= ) x,0leqslant xlt 1 2-x,1leqslant xleqslant 2 0, .-|||-求X的数学期望E(X).

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