a=[4,-1,2,-4,-9],执行命令[x for x in a if x>0]的返回值是()
举一反三
- 以4，9，1为为插值节点，求\(\sqrt x \)的lagrange的插值多项式 A: \( {2 \over {15}}(x - 9)(x - 1) + {3 \over {40}}(x - 4)(x - 1) + {1 \over {24}}(x - 4)(x - 9)\) B: \( - {2 \over {15}}(x - 9)(x - 1) + {3 \over {40}}(x - 4)(x - 1) + {1 \over {24}}(x - 4)(x - 9)\) C: \( - {2 \over {15}}(x - 9)(x - 1) + {3 \over {40}}(x - 4)(x +1) + {1 \over {24}}(x - 4)(x - 9)\) D: \( - {2 \over {15}}(x - 9)(x - 1) + {3 \over {40}}(x - 4)(x - 1) - {1 \over {24}}(x - 4)(x - 9)\)
- 已知列表 x = [1, 2, 3],那么执行语句 x.insert(0, 4)之后,x的值为___________。 A: [1, 2, 4,3] B: [1, 2, 3] C: [4, 1, 2, 3] D: [1,2, 3, 4]
- 已知x={1:1,2:2}，那么执行语句x[2]=4之后，x的值为
- 【单选题】A={{1,2},{3,4}};A[[2]]=A[[1]];A[[2,1]]=x; A为 A. {{1,2},{x,2}} B. {{1,2},{x,4}} C. {{3,4},{x,2}} D. {{3,4},{x,4}}
- 同时掷2颗均匀骰子，X表示点数大于4出现的个数，则以下结果正确的是 A: X服从二项分布 B: P(X=0)=P(X=1) C: P(X=1)=4/9 D: P(X=0)=1/9 E: P(X=2)=4/9 F: P(X>;0)=1 G: P(X<;2)=5/9 H: P(X>;1)>;0.5