How do you factor #9z ^ { 2} - 27z - 90#?

1 Answer
EZ as pi
May 7, 2018

#=9(z-5)(z+2)#

Explanation:

Start by dividing out the common factor of #9#

#9z^2 -27z-90#

#=9(z^2-3z-10)#

Now factorise the quadratic trinomial.
Find factors or #10# which subtract to give #3#.
The signs will differ, the larger factor must be negative.

#=9(z-5)(z+2)#

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