Slope of 2y = x + 5:-
This is y = 0.5 x + 2.5 in slope intercept form so its slope = 0.5
Slope of the line perpendicular to it = -1 / 0.5 = -2
it passes through (2 , 1) so we have
y- 1 = -2(x - 2)
y = -2x + 4 + 1
The answer is y = -2x + 5

the idea being, you multiply the "x" by some power of 10 that moves the repeating part to the left of the decimal point and the split it like above.
Exactly 10,000 it’s hard to explain though it’s really complicated
A, sub in a random number as x in all equations and solve, eg- x= 3
2-3= -1
3-2=1
-2 +3= 1
3-2=1
Hello,
x²+y²-10x+6y+18=0
==>(x²-2*5x+25)+(y²+2*3y+9)+18-25-9=0
==>(x-5)²+(y+3)²=16
Radius is 4.
Center (5,-3)