49=49开方后是什么是±7=±7或7=±7吗为啥错了

49是7的______倍，49的7倍是______．

17×(-7)÷(-17)×7等于（　　） A: 1 B: 49 C: -7 D: 7

对于双原子理想气体，其绝热指数（又称热容比）γ = Cp,m/CV,m等于 A: R B: 5/3 C: 7/5 D: 7/3

设A为m×n矩阵，B为n×m矩阵，且m＞n，令r(AB)=r，则( )。 A: r＞m B: r=m C: r＜m D: r≥m

Anh Hải làm việc ở đó bao lâu rồi? ( ) A: 4 năm B: 5 năm C: 6 năm D: 7 năm

求给定自然数m和n的最大公约数。请完善程序。 Private Sub Command1_Click() Dim m As Integer, n As Integer, r As Integer m = Text1.Text n = Text2.Text If m < n Then r = m: m = n: n = r Do r = m Mod n m = n n = r Loop Until__________ Text3.Text = m End Sub Private Sub Command2_Click() Dim m As Integer, n As Integer, r As Integer m = Text1.Text n = Text2.Text If m < n Then r = m: m = n: n = r r = m Mod n Do Until _______ m = n n = r r = m Mod n Loop Text3.Text =____ End Sub Private Sub Command3_Click() Dim m As Integer, n As Integer, r As Integer m = Text1.Text n = Text2.Text If m < n Then r = m: m = n: n = r Do r = m Mod n m = n n = r Loop While________ Text3.Text =______ End Sub Private Sub Command4_Click() Dim m As Integer, n As Integer, r As Integer m = Text1.Text n = Text2.Text If m < n Then r = m: m = n: n = r r = m Mod n Do While______ m = n n = r r = m Mod n Loop Text3.Text =____ End Sube73f1fd63959cc8362d8c82d419c2353.png

设A是m×n矩阵，B是n×m矩阵，E为m阶单位矩阵，若AB＝E，则（）。 A: r（A）＝m，r（B）＝m B: r（A）＝m，r（B）＝n C: r（A）＝n，r（B）＝m D: r（A）＝n，r（B）＝n

设A为m×n矩阵，B为n×m矩阵，E为m阶单位矩阵，若AB=E，则（）. A: r（A）=m，r（B）=m B: r（A）=m，r（B）=n C: r（A）=n，r（B）=m D: r（A）=n，r（B）=n

设[img=400x25]18032d3a2c9d92a.png[/img]，则[img=141x25]18032d3a352ea33.png[/img]的值为 A: 40/49 B: 16/49 C: 4/7 D: 3/7