Expanded form of equation of a circle

Find the equation of each circle with given centre and radius, write your answer without brackets in simplest form.

(1,2) r=4

I got x²+y²-2x-4y+1=0

Apparently that should be a -11 not a +1.

for (5,-1) r=3

I got x²+y²+10x+2y+23=0
That should be a +17, not a +23.

Unsure where I am going wrong....I have all the other terms correct....so don't understand where I am "falling down/going wrong" with the constant term.

Find the equation of each circle with given centre and radius, write your answer without brackets in simplest form.

(1,2) r=4

I got x²+y²-2x-4y+1=0

Apparently that should be a -11 not a +1.

for (5,-1) r=3

I got x²+y²+10x+2y+23=0
That should be a +17, not a +23.

Unsure where I am going wrong....I have all the other terms correct....so don't understand where I am "falling down/going wrong" with the constant term.