Question

What are the roots of y = x - 3x – 10?
-3 and -10
-2 and 5
2 and -5
3 and 10​

Answer 1

-2 and 5

Explanation:

If roots of a quadratic are "a" and "b", then (x-a) and (x-b) are factors. Then the quadratic can be written as ...

y = (x -a)(x -b) = x^2 -(a+b)x +ab

That is, the constant (-10) is the product of the roots, and the x-coefficient (-3) is the opposite of their sum.

In short, you want a solution pair that has a sum of 3. Only one answer qualifies: -2 and 5.