17.若$\frac{1}{a}<\frac{1}{b}<0$,则下列结论不正确的是( )
| A. | a2<b2 | B. | ab<b2 | C. | $\frac{1}{{a{b^2}}}<\frac{1}{{{a^2}b}}$ | D. | a+b<0 |
16.若a>0,b>0,且a+b=4则下列不等式中恒成立的是( )
| A. | a2+b2≥8 | B. | ab≥4 | C. | a2+b2≤8 | D. | ab≤2 |
15.已知实数x,y满足y=x2-2x+2,-1≤x≤1,则$\frac{y+3}{x+2}$的最小值是( )
| A. | $\frac{4}{3}$ | B. | $2\sqrt{13}-6$ | C. | 8 | D. | $\frac{5}{2}$ |
14.若l1:x+(m+1)y+6=0,l2:mx+2y+8=0的图象是两条平行直线,则m的值是( )
| A. | m=1或m=-2 | B. | m=1 | C. | m=-2 | D. | m的值不存在 |
13.若3sinα-4cosα=5,则tan(α+$\frac{π}{4}$)=( )
| A. | -$\frac{1}{7}$ | B. | $\frac{1}{7}$ | C. | -7 | D. | 7 |
12.直线$\left\{\begin{array}{l}{x=1+tsin70°}\\{y=2+tcos70°}\end{array}\right.$(t为参数)的倾斜角为( )
| A. | 70° | B. | 20° | C. | 160° | D. | 110° |
11.命题p:“?x0∈R“,x0-1≤0的否定¬p为( )
| A. | ?x∈R,x2-1≤0 | B. | ?x∈R,x2-1>0 | C. | ?x0∈R,x02-1>0 | D. | ?x0∈R,x02-1<0 |
10.若f(x)=x3,f'(x0)=3,则x0的值等于( )
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| A. | 1 | B. | -1 | C. | 1或-1 | D. | 2 |