20.函数y=f(x)(x∈(0,3))图象如图所示,若0<x1<x2<3,则有( )
A. | $\frac{f({x}_{1})}{{x}_{1}}$<$\frac{f({x}_{2})}{{x}_{2}}$ | B. | $\frac{f({x}_{1})}{{x}_{1}}$=$\frac{f({x}_{2})}{{x}_{2}}$ | ||
C. | $\frac{f({x}_{1})}{{x}_{1}}$>$\frac{f({x}_{2})}{{x}_{2}}$ | D. | 前三个判断都不正确 |
18.已知函数f(x)=$\left\{\begin{array}{l}{{x}^{2}+1(x≥2)}\\{2x-3(x<2)}\end{array}\right.$,则f(1)-f(3)=-11.
16.若复数z满足(1-i)z=1+i,则|z+i|=( )
0 250195 250203 250209 250213 250219 250221 250225 250231 250233 250239 250245 250249 250251 250255 250261 250263 250269 250273 250275 250279 250281 250285 250287 250289 250290 250291 250293 250294 250295 250297 250299 250303 250305 250309 250311 250315 250321 250323 250329 250333 250335 250339 250345 250351 250353 250359 250363 250365 250371 250375 250381 250389 266669
A. | 0 | B. | 1 | C. | 2 | D. | 3 |