# Tutor profile: Matteo M.

## Questions

### Subject: Pre-Calculus

Consider the function $$f(x) = \frac{x+1}{x-1} $$ with $$x \in R$$ Which of the following statements is true? a) The function is defined for every real value of x. b) The function isn't defined for x=1 and x=-1 c) The function is defined for every real value except x = -1 d) The function is defined for every real value except x = 1

d is true. The function isn't defined for x=1 because for this value of x the denominator is equal to zero. For x=-1, the function is defined, and its value is zero.

### Subject: Basic Math

What is the result of 23 (12+3)?

The multiplication symbol can sometimes be implied, so the equation can be rewritten 23 X (12+3). Normally multiplications must be solved before sums, but in this case the sum is inside brackets, which makes it prioritary. So we have: 23 X 15 = 345

### Subject: Physics

What does it means that energy in a quantum mechanical system is quantized?

It means that the system can only assume discrete energy levels, instead of the continuous spectrum of classical physics.

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