X2+y2-6x+2y-39=0 what is the radius and the center

(centre = (3, - 1 ) and radius = 7

Step-by-step explanation:

The equation of a circle in standard form is

(x - h)² + (y - k)² = r²

where (h, k) are the coordinates of the centre and r is the radius

Given

x² + y² - 6x + 2y - 39 = 0 ( collect x/ y terms and add 39 to both sides )

x² - 6x + y² + 2y = 39

Using the method of completing the square

add ( half the coefficient of the x/ y terms )² to both sides

x² + 2(- 3)x + 9 + y² + 2(1)y + 1 = 39 + 9 + 1

(x - 3)² + (y + 1)² = 49 ← in standard form

with centre (3, - 1 ) and r = = 7

70

step-by-step explanation:

2*5=10

4*15=60

60+10=

70