What is the equation of a circle whose center is (4 6) and whose radius is 4 cm?

The equation for a circle is (x-h)^2+(y-k)^2 = r^2 
The h part in with the x is your x coordinate and the k part in with the y is your y coordinate. The r stands for the radius but be careful you have to square it.
so:
(x-(4))^2 +(y-(6)^2 = 16
I like to add the parenthesis around the "plugged in" numbers to help me remember negatives if I have any.  

-2x + 7 = 7

subtract 7 from both sides.

-2x = 0

divide both sides by -2.

x = 0

the value of x is equal to 0.