15.cos(-225°)+sin(-225°)等于( )
| A. | $\frac{\sqrt{2}}{2}$ | B. | -$\frac{\sqrt{2}}{2}$ | C. | 0 | D. | $\sqrt{2}$ |
10.若二次函数g(x)满足g(1)=1,g(-1)=5,且图象过原点,则g(x)的解析式为( )
| A. | g(x)=2x2-3x | B. | g(x)=3x2-2x | C. | g(x)=3x2+2x | D. | g(x)=-3x2-2x |
9.函数y=x2sinx导数为( )
0 240229 240237 240243 240247 240253 240255 240259 240265 240267 240273 240279 240283 240285 240289 240295 240297 240303 240307 240309 240313 240315 240319 240321 240323 240324 240325 240327 240328 240329 240331 240333 240337 240339 240343 240345 240349 240355 240357 240363 240367 240369 240373 240379 240385 240387 240393 240397 240399 240405 240409 240415 240423 266669
| A. | y'=2x+cosx | B. | y'=x2cosx | ||
| C. | y'=2xcosx | D. | y'=2xsinx+x2cosx |