15.二次函数y=x2-4x-5的图象关于直线x=-1对称的图象的表达式是( )
| A. | y=x2-16x+55 | B. | y=x2+8x+7 | C. | y=-x2+8x+7 | D. | y=x2-8x+7 |
14.点P是直线y=-x+4上一动点,O为原点,则线段OP的最小值为( )
| A. | 2 | B. | $\sqrt{2}$ | C. | 2$\sqrt{2}$ | D. | 4 |
13.
如图,P为等腰△ABC内一点,过点P分别作三条边BC、CA、AB的垂线,垂足分别为D、E、F,已知AB=AC=10,BC=12,且PD:PE:PF=1:3:3,则AP的长为( )
| A. | $\frac{4}{3}$ | B. | $\frac{20}{3}$ | C. | 7 | D. | 8 |
12.已知正比例函数y=(3m+2)x的图象过点(2,10),则m的取值为( )
| A. | 1 | B. | -1 | C. | $\frac{2}{3}$ | D. | -$\frac{2}{3}$ |
11.
如图,在?ABCD中,E为边CD上一点,将△ADE沿AE折叠至△AD′E处,AD′与CE交于点F,若∠B=52°,∠DAE=20°,则∠FED′的大小为( )
| A. | 20° | B. | 30° | C. | 36° | D. | 40° |
10.下列计算正确的是( )
0 294175 294183 294189 294193 294199 294201 294205 294211 294213 294219 294225 294229 294231 294235 294241 294243 294249 294253 294255 294259 294261 294265 294267 294269 294270 294271 294273 294274 294275 294277 294279 294283 294285 294289 294291 294295 294301 294303 294309 294313 294315 294319 294325 294331 294333 294339 294343 294345 294351 294355 294361 294369 366461
| A. | (2x2)3=2x5 | B. | $\sqrt{6}$÷$\sqrt{3}$=2 | C. | 3a2+2a=5a3 | D. | 2m•5n=10mn |