2.下列运算正确的是( )
| A. | 3$\sqrt{2}$-$\sqrt{2}$=3 | B. | 3$\sqrt{3}$×2$\sqrt{2}$=6$\sqrt{5}$ | C. | 3$\sqrt{5}$÷$\frac{1}{{\sqrt{3}}}$×$\sqrt{3}$=3$\sqrt{5}$ | D. | 3÷$\sqrt{\frac{2}{3}}$=$\frac{3}{2}\sqrt{6}$ |
1.
如图,在矩形ABCD中,对角线AC、BD交于点O,以下结论错误的是( )
| A. | ∠ABC=90° | B. | △OAD是等边三角形 | ||
| C. | OA=OB;OC=OB | D. | AC=BD |
20.下列运算正确的是( )
| A. | 3+$\sqrt{3}$=3$\sqrt{3}$ | B. | $\sqrt{{{(-2)}^2}}$=2 | C. | $\sqrt{50}$=$\sqrt{25+25}$=5+5=10 | D. | $\sqrt{4\frac{1}{9}}$=2$\frac{1}{3}$ |
19.与$\sqrt{2}$是同类二次根式的为( )
| A. | $\sqrt{8}$ | B. | $\sqrt{3}$ | C. | $\sqrt{12}$ | D. | $\sqrt{6}$ |
18.下列二次根式中的最简二次根式是( )
| A. | $\sqrt{9}$ | B. | $\sqrt{24}$ | C. | $\sqrt{30}$ | D. | $\sqrt{\frac{2}{3}}$ |
14.
如图,在周长为20cm的?ABCD中,AB≠AD,AC、BD相交于点O,OE⊥BD交AD于E,则△ABE的周长为( )
| A. | 10cm | B. | 8cm | C. | 6cm | D. | 4cm |
13.
如图,将矩形ABCD沿EF折叠,使点B,D重合,已知AB=3,AD=4,则
①DE=DF;②DF=EF;③△DCF≌△DGE;④EF=$\frac{15}{4}$.
上面结论正确的有( )
0 284211 284219 284225 284229 284235 284237 284241 284247 284249 284255 284261 284265 284267 284271 284277 284279 284285 284289 284291 284295 284297 284301 284303 284305 284306 284307 284309 284310 284311 284313 284315 284319 284321 284325 284327 284331 284337 284339 284345 284349 284351 284355 284361 284367 284369 284375 284379 284381 284387 284391 284397 284405 366461
①DE=DF;②DF=EF;③△DCF≌△DGE;④EF=$\frac{15}{4}$.
上面结论正确的有( )
| A. | 1个 | B. | 2个 | C. | 3个 | D. | 4个 |