1.设a>-b,则下列不等式中,成立的是( )
A. | a(a+b)2<-b(a+b)2 | B. | a(a+b)2>-b(a+b)2 | C. | a(a+b)2≤-b(a+b)2 | D. | a(a+b)2≥-b(a+b)2 |
20.下列结论中,成立的是( )
A. | 若a≠b,则a2≠b2 | B. | 若a2≠b2,则a≠b | C. | 若a2>b2,则a>b | D. | 若a>b,则a2>b2 |
17.解不等式组:$\left\{\begin{array}{l}{2(x-6)>3-x}\\{\frac{2x-1}{3}-\frac{5x+1}{2}≤1}\end{array}\right.$.
13.已知$\frac{co{s}^{2}α-si{n}^{2}α}{sinα-cosα}$=$\frac{\sqrt{2}}{4}$,则sinαsin($\frac{π}{2}$+α)等于( )
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A. | -$\frac{1}{4}$ | B. | $\frac{5}{8}$ | C. | -$\frac{7}{16}$ | D. | $\frac{9}{16}$ |