Question 1169736: On an exam, Julie was asked to factor:
9z^2 + 27z + 18
She incorrectly answers:
9z^2 + 27z + 18
= (3z + 6)(3z + 3)
= 3(z + 2)(z + 1)
If this were an 8 point problem, how many points would you take off?
Why?
Found 2 solutions by ikleyn, josgarithmetic:
Answer by ikleyn(52866)   (Show Source):
You can put this solution on YOUR website! .
I am not a teacher,
and the problem is not solved.
So we see a lack of knowledge and a lack of attention.
She even did not try to check her solution.
I would take off from 4 to 5 points, leaving the rest for her diligence . . .
The major part she needs to be explained is CHECKING her work.
I'd say
"you did a great job, but forgot to check yourself. Be more attentive next time.
Everybody can make a mistakes, but in Math, everyone MUST know HOW to check himself or herself
and HOW to find and fix his or her mistakes".
Answer by josgarithmetic(39628)  (Show Source):
You can put this solution on YOUR website! The took just one strange and unnecessary step to reach a correct factorization. Take off maybe not more than 2 points from the 8-points value.
The factor, 3, should have been the first factor to have been isolated.
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