First, observe the rule of operator precedence, i.e. BEDMAS (brackets,exponents, division/multiplication, addition/subtration) in that order.
Q1.
I suspect the expression should have been written as (x+5)/(x+3) to be interpreted correctly.
Based on that, we know that the new denominator is x², and denote the new numerator as N, then equate the two equivalent fractions:
(x+5)/(x+3) = N / x²
Cross multiply and solve for N:
N = (x+5)*x²/(x+3)
=(x³+4x²)/(x+3)
Unfortunately N is not a polynomial.
For Q2 and Q3, I suggest you correct the expressions according to the BEDMAS precedence rules and repost.
question 1: build the fraction x+5/x+3 to an equivalent fraction whoes denominator is x^2
question 2: simplify (x^2+6x+9)(3-x)/(x-3)(2x+6)
question 3. find the product in simplest from x^3-9x/x^5+27x^2 * x^2-3x+9/x^2+3x
2 answers
typo:
N = (x+5)*x²/(x+3)
=(x³+5x²)/(x+3)
N = (x+5)*x²/(x+3)
=(x³+5x²)/(x+3)