9x²-18x+8 Lets see here?

Question

9x²-18x+8

Dangit!

(3x )(x )

the eight is confusing I added the first and third term got 72 should I get a number that big

Answer 1

two possibilities for x, 3x3 or 9x1

for the other term, 8x1 or 4x2

trial and error

(3x  8 )(3x   1) no

(3x  1 )(3x   8) no

(3x  4 )(3x   2)  looks good

(3x - 4 )(3x - 2) ok

.

Answer 2

Find factors of 9x² : 3x, 3x  OR  9x, x

They are factors because when you multiply the pair, say 3x * 3x, you get 9x².

(3x - 2 ) (3x - 4)

I got the 2 and 4 because they are factors of 8.

I knew to use minus signs because you need to add two numbers to get -18x and when you multiply the last two, you have to get positive 8.

It's a lot of trial and error and practice to get good at it but I know you'll get there.  Good luck !

Answer 3

Write down factors of the first and last number to find a combination of multiplying and adding to get the middle term while keeping in mind the first and last terms:

9 = 3,3,9,1 factors

8=4,2,8,1 factors

middle is18 = 12+6 =3*4 + 3*2

therefore (3x-?)(3x-?)

gives (3x-4)(3x-2) the answer

Answer 4

You need 3x in both places, not 3x and x.

(3x - 4)(3x - 2) = 9x^2 - 6x - 12x + 8 = 9x^2 - 18x + 8

Answer 5

9x²-18x+8

(3x - 4)(3x - 2)

You to remember to factor in the 3x when you multiply items. And that you forgot the other 3.