How do you find the zeroes for f(x) = x^2 – 9x – 70?

Mar 28, 2018

$x = - 14$ and $x = 5$

Explanation:

We need to think of two numbers, that, when I add them, sum up to $- 9$, and when I multiply them, have a product of $- 70$. Since the product is negative, we know the signs must be different.

Through some thought, we arrive at $- 14$ and $5$ as our two numbers, because

$- 14 + 5 = - 9$ and

$- 14 \cdot 5 = - 70$

Thus, our equation is as follows:

$\left(x - 14\right) \left(x + 5\right) = 0$

To find the zeroes, we take the opposite signs to get

$x = 14$ and $x = - 5$

Hope this helps!

Mar 29, 2018

$f \left(x\right) = {x}^{2} - 9 x - 70 = 0$