Question mark sign in math

[Violetz]

I have seen some exam papers don't consist question mark sign when writing questions

Solve the following equation
Subtract five from both sides of the equations
Simplify each side

Is using question mark incorrect as in the above sentences?

 

[emsr2d2]

None of those require a question mark. They are all instructions (imperatives). They should all, however, end with a full stop, as should your opening sentence.

 

[teechar]

I have seen some exam papers that don't consist use a question mark sign when writing for some questions.
Is using question a mark incorrect as in the above sentences?

See above.