S is increasing function or not?

Question

Consider the following statements. 
S₁: f(x) = x⁵ + 3x - 1 is an increasing function for all values of x. 
S₂: f(x) = 1-x³-x⁹ is decreasing function for all values of x where x 0. 

Which of the above statements are TRUE.

• A-S₁ only
• B-S₂ only
• C-Both S₁ and S₂
• D-Neither S₁ nor S₂

Comments

what is the domain of x?

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This is complete question.

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This is complete question.

ok, then i am out of discussion