9.
如图,某数学兴趣小组将长为6,宽为3的矩形铁丝框ABCD变形为以A为圆心,AB为半径的扇形(忽略铁丝的粗细),则所得扇形BAD的面积为( )
| A. | 3$\sqrt{3}$ | B. | 18 | C. | 9 | D. | 6$\sqrt{3}$ |
6.己知代数式2y2+3y+7的值是8,则代数式4y2+6y-9的值是( )
| A. | 2 | B. | 17 | C. | 7 | D. | -7 |
5.下列运算正确的是( )
| A. | ab2+a2b=2a2b2 | B. | -3ab+ab=-4ab | C. | a2-a=a | D. | m2n-nm2=0 |
4.下列各式中,去括号正确的是( )
| A. | x2-(x-y+2z)=x2-x+y+2z | B. | x-(-2x+3y-1)=x+2x+3y+1 | ||
| C. | 3x+2(x-2y+1)=3x-2x-2y-2 | D. | -(x-2)-2(x2+2)=-x+2-2x2-4 |
1.
已知函数y=k1x+b1与函数y=k2x+b2的图象如图所示,则方程组$\left\{\begin{array}{l}{{k}_{1}x+{b}_{1}-y=0}\\{{k}_{2}x+{b}_{2}-y=0}\end{array}\right.$的解为( )
| A. | $\left\{\begin{array}{l}{x=-1}\\{y=2}\end{array}\right.$ | B. | $\left\{\begin{array}{l}{x=-1}\\{y=5}\end{array}\right.$ | C. | $\left\{\begin{array}{l}{x=1}\\{y=4}\end{array}\right.$ | D. | $\left\{\begin{array}{l}{x=5}\\{y=5}\end{array}\right.$ |
20.
如图,已知AB∥CD,DE⊥AC,垂足为E,∠A=130°,则∠D的度数是( )
0 280237 280245 280251 280255 280261 280263 280267 280273 280275 280281 280287 280291 280293 280297 280303 280305 280311 280315 280317 280321 280323 280327 280329 280331 280332 280333 280335 280336 280337 280339 280341 280345 280347 280351 280353 280357 280363 280365 280371 280375 280377 280381 280387 280393 280395 280401 280405 280407 280413 280417 280423 280431 366461
| A. | 20° | B. | 40° | C. | 50° | D. | 70° |