15.下列结论中正确的是( )
| A. | 若a>0,则(a+1)($\frac{1}{a}$+1)≥2 | B. | 若x>0,则lnx+$\frac{1}{lnx}$≥2 | ||
| C. | 若a+b=1,则a2+b2≥$\frac{1}{2}$ | D. | 若a+b=1,则a2+b2≤$\frac{1}{2}$ |
14.已知f(x)=ax3+bx9+2在区间(0,+∞)上有最大值5,那么f(x)在(-∞,0)上的最小值为( )
| A. | -5 | B. | -1 | C. | -3 | D. | 5 |
13.下列函数中,既是奇函数又在区间(0,+∞)上单调递增的函数为( )
| A. | y=x3 | B. | y=lgx | C. | y=|x| | D. | y=x-1 |
11.定义在R上的奇函数f(x)满足:对任意的x1,x2∈(-∞,0),(x1≠x2),都有$\frac{f({x}_{1})-f({x}_{2})}{{x}_{1}-{x}_{2}}$<0,则下列结论正确的是( )
0 234196 234204 234210 234214 234220 234222 234226 234232 234234 234240 234246 234250 234252 234256 234262 234264 234270 234274 234276 234280 234282 234286 234288 234290 234291 234292 234294 234295 234296 234298 234300 234304 234306 234310 234312 234316 234322 234324 234330 234334 234336 234340 234346 234352 234354 234360 234364 234366 234372 234376 234382 234390 266669
| A. | f(log3π)>f(log2$\sqrt{3}$)>f(log3$\sqrt{2}$) | B. | f(log2$\sqrt{3}$)>f(log3$\sqrt{2}$)>f(log3π) | ||
| C. | f(log3$\sqrt{2}$)>f(log2$\sqrt{3}$)>f(log3π) | D. | f(log2$\sqrt{3}$)>f(log3π)>f(log3$\sqrt{2}$) |