Express number in standard form 8.023×10^-7

0.0000008023..  This is because since its negative I know that the decimal place will move seven times to the left (think of a number line; the negatives are on the left and the positive are on the right).  Therefore you should get 0.0000008023 as this number in standard form because you moved the decimal place seven to the left.

X^2 - 4x +(4/2^2) + y^2 + 8y + (8/2^2) = -4 + (4/2^2) + (8/2^2)(x + 2)^2 + (y + 4)^2 = -4 + 4 + 16your center is (-2, -4) and the radius is the sqrt of -4 + 4 + 16 which is 4