Processing Math: Done

From Förberedande kurs i matematik 1

What we need to do is to rewrite the equation in the standard form

x−a2+y−b2=r2 

because then we can read off the circle's centre ab  and radius, r.

In our case, we need only take out the factor  3 from the brackets on the left-hand side

3x−12+3y+72=32x−312+32y+372=9x−312+9y+372

and then divide both sides by 9 , so as to get the equation in the desired form:

x−312+y+372=910 

Because the right-hand side can be written as 9102  and the term y+372  as

y−−372 , the equation describes a circle with its centre at 31−37  and radius 910=310