Fo you think all extracurricular activities are equally useful for students to succeed?

What is the main idea of this paragraph

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

Based on the cause-and-effect relationship in this sentence, what is the meaning of the word revert? the brownies kali made using a new recipe were too dry, so she reverted to her original recipe. a) to alter or change completely; revise b) to dispose of or remove; to throw away c) to prepare for something; assemble or make d) to go back to a previous state or practice