Question

the modulus of an integer x is 9, then. a. x=9 only. b.x=-9 only. c.x=+-. d.none of these

Answer 1

|x| = 9;
x² = 81;
x = (+-) 9; [ Here (+-) sign represents plus-minus sign]
Answer C.

Answer 2

As there is modules, x can be equal to either +9 or -9. We can see the situation while solving quadratic equations and find square roots - we get two answers one positive and one negative.