18.三个半径为R的圆两两外切,则夹在三个圆之间部分的面积是( )
| A. | $\frac{\sqrt{3}}{2}$R2-$\frac{1}{2}$πR2 | B. | $\sqrt{3}$R2-$\frac{2}{3}$πR2 | C. | ($\sqrt{3}$-1)R2 | D. | $\sqrt{3}$R2-$\frac{1}{2}$πR2 |
15.下列各式中,正确的是( )
| A. | (-$\frac{2}{3}$)-2=$\frac{4}{9}$ | B. | $\frac{-a+b}{c}$=-$\frac{a+b}{c}$ | ||
| C. | ($\frac{2{a}^{2}}{3b}$)3=$\frac{8{a}^{5}}{9{b}^{3}}$ | D. | $\frac{-a-b}{-a+b}$=$\frac{a+b}{a-b}$ |
14.下列各式从左到右的变形是因式分解的是( )
| A. | a(b-c)=ab-ac | B. | x2-2x+3=(x-1)2+2 | C. | x2-4=(x+2)(x-2) | D. | (x+1)(x+2)=x2+3x+2 |
13.下列从左边到右边的变形,属于因式分解的是( )
| A. | (2-x)(2+x)=4-x2 | B. | -a(a-b)=-a2+ab | C. | m2-n2=(m+n)(m-n) | D. | (1-x)2=(x-1)2 |
12.要使分式$\frac{1}{{{x^2}-1}}$有意义,则x应满足的条件是( )
| A. | x≠1 | B. | x≠-1 | C. | x≠0 | D. | x≠±1 |
11.若分式$\frac{6}{2x-1}$的值为2,则x的值为( )
| A. | 2 | B. | -2 | C. | 1 | D. | -1 |
10.下列计算正确的是( )
0 292167 292175 292181 292185 292191 292193 292197 292203 292205 292211 292217 292221 292223 292227 292233 292235 292241 292245 292247 292251 292253 292257 292259 292261 292262 292263 292265 292266 292267 292269 292271 292275 292277 292281 292283 292287 292293 292295 292301 292305 292307 292311 292317 292323 292325 292331 292335 292337 292343 292347 292353 292361 366461
| A. | 1-2=-2 | B. | 2-2=-$\frac{1}{4}$ | C. | (-2)-1=-$\frac{1}{2}$ | D. | (-$\frac{1}{2}$)-1=-$\frac{1}{2}$ |