Question

Which number could not be a value of x?

Answer 1

21

Explanation:

The sum of two sides of a triangle must be greater than the third side

Answer 2

21

Explanation:

The values for the third side of a triangle must be greater than the difference of the two other sides and less than the sum of the two other sides

12 -8 < x < 12+8

4 < x < 20

The third side cannot be 21