Question

How do you factor #y=z^2 + 3z - 4 #?

Answer 1

Factors of `z^2+3z−4` are `(z-1)(z+4)`

Explanation:

To find the factors of `az^2+bz+c`, one should find factors of `a*c` whose sum is `b`.

As the function is `z^2+3z−4`, one should find factors of `1*(-4)` or `-4` whose sum is `3`.

These are `-1` and `4`. Hence splitting middle term this way.

`z^2+3z−4` = `z^2-1z+4z−4` or

`z(z-1)+4(z-1)` or `(z-1)(z+4)`