Is this trinomial factorable r^2-15r+56

(r - 8) (r - 7)

Step-by-step explanation:

Consider the factors of the constant term (56) which sum to give the coefficient of the r - term ( - 15)

The factors are - 8 and - 7, hence

r² - 15r + 56 = (r - 8) (r - 7) ← in factored form