Question

Not sure what's the answer

Factor the following polynomial. Check your answers using FOIL.
x² + 3x - 70
O(x+10) (x-7)
(x - 1)(x-9)
(x - 3)(x - 70)
(x - 10) (x + 7)

Answer 1

The answer would be (x+10)(x-7)

Explanation:

The way I learned it was the numbers would multiply to get 70, but add to get 3. Multiples of 70 are 1, 2, 5, 7, 10, 14, 35, 70. Out of these the only one that works is 10 and 7. Using foil, we get x^2-7x+10x-70 which becomes x^2+3x-70