Đường tròn (C): x² + y² + 12x – 14y + 4 = 0 viết được dưới dạng:

A. (x + 2)² + (y – 3)² = 4;          

B. (x + 2)² + (y – 3)² = 9;          

C. (x – 2)² + (y + 3)² = 4;          

D. (x – 2)² + (y + 3)² = 9.

A. (x + 3)² + (y – 1)² = $\sqrt{5}$ ;                

B. (x – 3)² + (y + 1)² = $\sqrt{5}$ ;                

C. (x – 3)² + (y + 1)² = 5;          

D. (x + 3)² + (y – 1)² = 5.

A. 4x – 3y + 5 = 0; 4x – 3y – 45 = 0;            

B. 4x + 3y + 5 = 0; 4x + 3y + 3 = 0;              

C. 4x + 3y + 29 = 0;                  

D. 4x + 3y + 29 = 0; 4x + 3y – 21 = 0.

A. 5;            

B. 7;            

A. I(3; –1), R = 4;           

D. I(–3; 1), R = 2.

A. I(–8; 4), R = $\sqrt{91}$ ;                

B. I(8; –4), R = $\sqrt{91}$ ;                

C. I(–8; 4), R = $\sqrt{69}$ ;                

D. $I(-\frac{1}{2};\frac{1}{4}),R=1$

A. m = 2;              

B. m = –1;             

C. m = 1;               

D. m = –2.