Is it possible to factor #y=9x^2 - 21x + 10 #? If so, what are the factors?
Find the factors of 9 and 10 which combine and add up to 21. The signs will be the same, they are both minus.
One clue is to look at the size of the coefficient of the middle term.
That is an indication that we are using the "middle factors"
Factors of 9: 1, 3 9. Factors of 10: 1,2,5,10.
Try the cross-products of
The numbers in the top row are in one bracket.
The numbers in the bottom row are in one bracket.
Multiply out for yourself to see how the numbers work.
To determine that a given quadratic polynomial like
can be factorised or not in
The pol. can have factors in
In our case,
Therefore, the poly.