Two sides of a triangle have lengths 4 and 7. Which of the following can NOT be the length of the third side

Answer 1

Can't see your choices , but .......

Any side of a triangle must be less than the sum of the other two sides
so if your third side is x , where x is a positive number
x < 4+7 AND 7 < 4+x AND 4 < 7+x

x < 11 AND x > 3 AND x > -3 <----- already contained in x > 3

so
3 < x < 11 , that is, your third side must be any number between 3 and 11

So anything outside that domain would not form a triangle

Answer 2

7-4 < x < 7+4
so the 3rd side must be between 3 and 11