How do you factor 9x^2+18x-16?

You must first figure out what times what equals in this case (-16)
So we have 4X-4=-16 and -8X2=-16 so know we know that one of these is our answer. Then you must figure out what plus what equals 18 or in this case what minus what equals 18. then you must find out what is Squared.
therefore the answer is
9x^2+18x-16
(3x+8)(3x-2)
Now check it
3x*3x=9x^2
8*3x=24
3x*-2=(-6) and lastly
8*-2= -16
so 9x^2+24x-6x-16=9x^2+18x-16

When there are alternating signs, that means you're going to have the basic form of (ax-b)(cx+d)
These I just tend to do quick trial and error in my head, these are mostly practice or using calculators, or quadratic formula if your stumped lol
but it seems to be:

(3x-2)(3x+8).

I honestly have no idea how to do these easily without the quadratic formula or trial and error. Luckily I was always good with mental math, but if you're not, these can be tough for a while.

9x^2 + 18x - 16
= 9x^2 + 24x - 6x - 16
= (9x^2 + 24x) - (6x + 16)
= 3x(3x + 8) - 2(3x + 8)
= (3x + 8)(3x - 2)

9x(x+2) -16

9x^2+18x-16 = 9x^2+ 24x - 6x-16 =3x(3x+8) - 2(3x+8)
= (3x+8)(3x-2).

=9(x-2/3)(x+8/3)=
=(3x-2)(3x+8)