Question

How do you factor `x^2 + x - 42`?

Answer 1

`(x+7)(x-6)`

Explanation:

Factoring quadratic equations is usually a trial and error thing (at least for me). Here's how I answered it in my head.

First, I thought of the factors of `x^2`. The only possible ones are `x` and `x`.

Next, I thought: What two factors of -42 are equal to `1` (since that is the coefficient of `x`) when added?
The two numbers that I thought of were -6 and 7, since `-6+7=1`.

Therefore, my factors are `(x+7)` and `(x-6)`.

You can try double-checking this by multiplying `(x+7)` and `(x-6)`.

If you don't like "guessing" the factors, you can also use the quadratic formula for that. Though I suggest you don't since it is time consuming.
`x=(-b±sqrt(b^2-4ac))/(2a)`

Answer 2

`(x-6)` `(x+7)`

Explanation:

Cross factorise it! It's a little hard to explain so you should watch a video which would help you understand even better.

To check:
Expand the brackets! You will get the same answer.