15.已知函数f(x)=a-$\frac{1}{{{2^x}+1}}$.
(1)若f(x)为奇函数,求a的值;
(2)证明:不论a为何值f(x)在R上都单调递增;
(3)在(1)的条件下,求f(x)的值域.
(1)若f(x)为奇函数,求a的值;
(2)证明:不论a为何值f(x)在R上都单调递增;
(3)在(1)的条件下,求f(x)的值域.
13.设集合A={1,2},则下列正确的是( )
0 224265 224273 224279 224283 224289 224291 224295 224301 224303 224309 224315 224319 224321 224325 224331 224333 224339 224343 224345 224349 224351 224355 224357 224359 224360 224361 224363 224364 224365 224367 224369 224373 224375 224379 224381 224385 224391 224393 224399 224403 224405 224409 224415 224421 224423 224429 224433 224435 224441 224445 224451 224459 266669
| A. | 1∈A | B. | 1∉A | C. | {1}∈A | D. | 1⊆A |