Evaluate the left-hand side to find the value of 'a' in this equation in its simplest form

Nine more than four times a number is the same as one less than twice the number. find the number?

If f(x)=-x^2+6x-1 and g(x)=3x^2-4x-1,find(f+g)(x)

1- what do you think the product of a nonzero rational number and an irrational number is? is it rational or irrational? make use of variables, the closure property of integers, and possibly a proof by contradiction to prove your hypothesis.2- why do we have to specify that the rational number must be nonzero when we determine what the product of a nonzero rational number and an irrational number is? if the rational number were 0, would it give us the same result we found in the first question?