Numbers L1

If X is between -3 and -1, and Y is between -1 and 1, then X2 - Y2 is in between which of the following?

  1. -9 and 1
  2. -9 and -1
  3. 0 and 8
  4. 0 and 9

Answer

-3 < X < -1, so 9 < X2 < 1

-1 < Y < 1, so 1 < Y2 < 1

Subtracting,

8 < X2 - Y2 < 0

The correct option is C.