Using the AC method to factor. When factoring x^2+bx+c, sometimes there can be many factors of c. Example: Factor. If you recall, if a =1 then we factor c and we look for the pairs of factors that sum to the middle term, b.
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Using the AC method to factor
When factoring x^2+bx+c, sometimes there can be many factors of c
If you recall, if a =1 then we factor c and we look for the pairs of factors that sum to the middle term, b
So we want to find the factors of 442 that add up to -9. There are many factors of 442 so let’s use our calculator to help us.
In this case, we want to find the factors of 442
Press the following sequence of buttons on your calculators
Y=, 442, /, x, 2nd, GRAPH
You should see the following on your screen (before pressing 2nd GRAPH)
After pressing 2nd GRAPH you should see something like this:
If you don’t see this, then go to the next slide for trouble shooting. If you do see this, then skip the next slide.
Press 2nd, then WINDOW
You should see the following
Set your independent to Auto, your table start at 0, and your triangle table = to 1v
Now press 2nd and then GRAPH
Then you should see what we got before
Scroll down to look through the factors. We are looking for the pair that add OR subtracts to -9
The only pair that this can happen with is 17 and 26. Since we want it to add to -8, the factors should be -26 and +17
So therefore, our factors are:
Multiply it out to make sure that it checks!