6.函数f(x)=($\sqrt{1+x}$+$\sqrt{1-x}$+2)($\sqrt{1-{x}^{2}}$+1)的值域是( )
| A. | [2+$\sqrt{2}$,8] | B. | [2+$\sqrt{2}$,+∞) | C. | [2,+∞) | D. | [2+$\sqrt{2}$,4$\sqrt{2}$] |
4.以正方形的一条边的两个端点为焦点,且过另外两个顶点的椭圆离心率为( )
| A. | $\sqrt{2}$-1 | B. | $\sqrt{2}$ | C. | $\frac{\sqrt{2}-1}{2}$ | D. | $\frac{\sqrt{3}-1}{2}$ |
3.已知(x+1)(x-2)9=a0+a1(x-1)+a2(x-1)2+…+a10(x-1)10,则a8=( )
| A. | 18 | B. | 36 | C. | 135 | D. | 144 |
2.设x,y满足约束条件$\left\{\begin{array}{l}3x+y-2\;≤\;0\;\\ y-x\;≤\;2\;\\ y\;≥\;-x-1\;,\;\;\end{array}\right.$则z=y-2x的最大值( )
0 229513 229521 229527 229531 229537 229539 229543 229549 229551 229557 229563 229567 229569 229573 229579 229581 229587 229591 229593 229597 229599 229603 229605 229607 229608 229609 229611 229612 229613 229615 229617 229621 229623 229627 229629 229633 229639 229641 229647 229651 229653 229657 229663 229669 229671 229677 229681 229683 229689 229693 229699 229707 266669
| A. | $\frac{7}{2}$ | B. | 2 | C. | 3 | D. | $\frac{11}{2}$ |