18.下列各式中,不能用平方差公式计算的是( )
| A. | (2x-y)(2x+y) | B. | (-x+y)(x-y) | C. | (b-a)(b+a) | D. | (x-y)(-y-x) |
14.下列各式中,有意义的是( )
0 282092 282100 282106 282110 282116 282118 282122 282128 282130 282136 282142 282146 282148 282152 282158 282160 282166 282170 282172 282176 282178 282182 282184 282186 282187 282188 282190 282191 282192 282194 282196 282200 282202 282206 282208 282212 282218 282220 282226 282230 282232 282236 282242 282248 282250 282256 282260 282262 282268 282272 282278 282286 366461
| A. | $\sqrt{\frac{1}{9}-1}$ | B. | $\sqrt{-2}$ | C. | $-\sqrt{{{({-6})}^3}}$ | D. | $\sqrt{{{({-3})}^2}}$ |