How do you factor #x^2 + x - 42#?
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
Next, I thought: What two factors of -42 are equal to
The two numbers that I thought of were -6 and 7, since
Therefore, my factors are
You can try double-checking this by multiplying
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.
Cross factorise it! It's a little hard to explain so you should watch a video which would help you understand even better.
Expand the brackets! You will get the same answer.