Which of the following expression is a perfect square? A. 4x
B. 4x2
C. 6x4
D. 8x

Plz which expression is equivalent to the expression below?

Find the center and the radius of the circle with the equation: x^2-2x+y^2+4y+1=0?

How do i start to solve? would appreciate a walk-thru! a bird sitting 16ft above the ground in an apple tree dislodges an apple. after how many seconds does the apple land on the ground? (assuming that no branches will interfere with it's fall)