How do you factor #18x^2-9x-14#?
2 Answers
Explanation:
The factors of 18 are (1 and 18), (-1 and -18), (2 and 9), (-2 and -9), (3 and 6), and (-3 and -6).
So, it could either be:
The factors of -14 are (1 and -14), (-1 and 14), (-2 and 7), or (2 and -7)
Now we need to combine a set of factors of -14 and 18 that would add to give -9.
These are:
-14 - (-2 and 7)
18 - (-3 and -6)
So,
Dividing a negative out of each bracket gives the factors as:
Explanation:
Find factors of
This involves a bit of trial and error to find them.
These are the correct factors, now look at the signs.
The difference needs to be
This gives the factors as:
An alternative method is to multiply
Find factors which are close to the square root of
A difference of
A bit of trial and error results in
This gives us a clue as to the factors we need to work towards.
