Answer:
x² - 10x + 21 = 0
Step-by-step explanation:
We have to write an equation that has x = 3 and x = 7 are the only roots.
Therefore, the factors of the equation will be (x - 3) and (x - 7).
So, we can write the equation as (x - 3)(x - 7) = 0
⇒ x(x - 7) - 3(x - 7) = 0
⇒ x² - 10x + 21 = 0 (Answer)