Homework Help

Completely factor the following expression. `z^2 + 15z - 54`

user profile pic

loishy | Student, Grade 10 | Salutatorian

Posted March 11, 2013 at 2:56 PM via web

dislike 4 like

Completely factor the following expression.

`z^2 + 15z - 54`

1 Answer | Add Yours

user profile pic

durbanville | High School Teacher | (Level 1) Educator Emeritus

Posted March 11, 2013 at 4:19 PM (Answer #1)

dislike 1 like

To factorize `z^2 +15z-54` you need to establish the factors that are relevant between the first and the third terms:

`z^2 = z times z` and the factors of 54 are (1 x 54, 2 x 27, 3 x 18,

6 x 9, ) . Use must establish which of these combinations will render a middle term of +15

The only ones that will work are 3x18. Care must be taken not to use 6 x9 which seem s most obvious but would render +54 as the third term .

`therefore= (z-3)(z+18)`

Sources:

Join to answer this question

Join a community of thousands of dedicated teachers and students.

Join eNotes