Which of the following is the equation of a circle whose center is at the origin and whose diameter has endpoints (-1,2) and (1,-2)? a.) x^2 + y^2 = 2 b.) x^2 + y^2 = 3 c.) x^2 + y^2 = 4 d.) x^2 + y^2 = 5

Which statement shows that 6.24 is a rational number? a. 6.24 = 6.242424 b. 6.24 = 6.24 c. 6.24 = 68⁄33 d. 6.24 = 66⁄25

Which of the following statements is true? a. the irrational number system is not closed under multiplication, because the product of two irrational numbers is always a rational number. b. the irrational number system is not closed under multiplication, because the product of two irrational numbers is not always an irrational number. c. the irrational number system is closed under multiplication, because the product of two irrational numbers is always an irrational number. d. the irrational number system is closed under multiplication, because the product of two irrational numbers is always a rational numbers. reset submit

Why is causation so much more difficult to prove than correlation?