Question

Why would the first step be to add 5 to both sides

Answer 1

By equating the polynomial equation to zero and factoring the polynomial, we can find its roots. (For a product to be equal to zero, at least one of its factors must be equal to zero.)

When the product of factors equals zero, one or more of the factors must also equal zero. Once the polynomial is factored, set each factor equal to zero and solve them separately