Find the center and radius of the circle.
1. (x-3)²+(y+6)² = 81
center:___ radius:___
2. (x-4)²+(y+1)² = 9
center:___ radius:___
3. (x+3)²+(y+3)² = 16
center:___ radius:___
4. (x-5)²+(y-7)² = 20
center:___ radius:___
5. x²-4x+y²-4y-8 = 0
center:___ radius:___
6. x²+y²-4x-6y+8 = 0
center:___ radius:___
7. x²+y²-4x-6y-15 = 0
center:___ radius:___

Transform into General form.
1. (x-2)²+(y-4)² = 36
2. (x-2)²+(y+1)² = 9
3. (x-6)²+(y-1)² = 81

Transfrom into Standard form.
1. x² + y² - 2x - 8y - 47 = 0
2. x² + y² - 8x + 4y + 11 = 0
3. x² + y² + 4x + 10y + 4 = 0
4. x² + y² + 18x + 14y + 105 = 0