8.下列长度的三根木棒首尾相接,能做成三角形的框架的是( )
| A. | 3cm,5cm,10cm | B. | 5cm,4cm,9cm | C. | 4cm,6cm,9cm | D. | 5cm,7cm,13cm |
4.
如图,在平面直角坐标系中,直线y=$\frac{3}{4}$x+6交x轴于点A,交y轴于点B,D1是线段AB的中点,过D1作D1E1⊥x轴于E1,连接BE1交OD1于D2;过D2作D2E2⊥x轴于E2,连接BE2交OD1于D3;过D3作D3E3⊥x轴于E3,…,如此继续,可以依次得到点D4,D5,…,Dn,分别记△BD1E1,△BD2E2,△BD3E3,…,△BDnEn的面积为S1,S2,S3,…Sn.则Sn为( )
| A. | $\frac{24}{(n+1)^{2}}$ | B. | $\frac{12}{(n+1)^{2}}$ | C. | $\frac{24}{{n}^{2}}$ | D. | $\frac{12}{{n}^{2}}$ |
3.比-1大的无理数是( )
| A. | 3.14 | B. | $-\sqrt{2}$ | C. | $\frac{22}{7}$ | D. | $-\frac{{\sqrt{2}}}{2}$ |
1.若a、b是有理数,则下列说法正确的是( )
0 286018 286026 286032 286036 286042 286044 286048 286054 286056 286062 286068 286072 286074 286078 286084 286086 286092 286096 286098 286102 286104 286108 286110 286112 286113 286114 286116 286117 286118 286120 286122 286126 286128 286132 286134 286138 286144 286146 286152 286156 286158 286162 286168 286174 286176 286182 286186 286188 286194 286198 286204 286212 366461
| A. | 若a2>b2,则a>b | B. | 若a>b,则a2>b2 | C. | 若|a|>b,则a2>b2 | D. | 若|a|≠|b|,则a2≠b2 |