If a and b are real numbers, then |a-b| is always, sometimes or never equal to |b-a| ?

Which matrix can be multiplied to the left of a vector matrix to get a new vector matrix ?

Apatient is given 50 mg dose of medicine the medicines effectiveness decreases every hour at a constant rate of 40% what is the exponential decay function that models this scenario how much medicine will be left in the patients system after 2 hours

Determine which expressions represent real numbers and which expressions represent complex number. asaaap! plis!