17.二次函数y=ax2+bx+c(a≠0)满足当x=1时,y的最大值为3,且当x≥m时,函数y随自变量x的增大而减小,则字母m的取值范围是( )
| A. | m≥3 | B. | m≤3 | C. | m≥1 | D. | m≤1 |
14.下列去括号正确的是( )
| A. | a-(b-c)=a-b-c | B. | a+b-(-c-d)=a+b+c+d | ||
| C. | m-2(p-q)=m-2p+q | D. | a+(b-c-2d)=a+b-c+2d |
12.一只不透明的袋子中装有5个黑球4个白球,这些球除颜色外都相同,搅匀后从中任意摸出1个球,摸到白球的概率为( )
0 286261 286269 286275 286279 286285 286287 286291 286297 286299 286305 286311 286315 286317 286321 286327 286329 286335 286339 286341 286345 286347 286351 286353 286355 286356 286357 286359 286360 286361 286363 286365 286369 286371 286375 286377 286381 286387 286389 286395 286399 286401 286405 286411 286417 286419 286425 286429 286431 286437 286441 286447 286455 366461
| A. | $\frac{1}{9}$ | B. | $\frac{1}{4}$ | C. | $\frac{4}{5}$ | D. | $\frac{4}{9}$ |