SOLUTION: I am trying to help my niece with her Algebra and both of us our totally stumped. Here is the example of the problems we are working. Can you please review and tell me how you go

Algebra ->  Matrices-and-determiminant -> SOLUTION: I am trying to help my niece with her Algebra and both of us our totally stumped. Here is the example of the problems we are working. Can you please review and tell me how you go      Log On


   

Question 580941: I am trying to help my niece with her Algebra and both of us our totally stumped. Here is the example of the problems we are working. Can you please review and tell me how you got the answer?
2z squared + 3Z =135
Thank you for your assistance.
I do appreciate it!
Jamie Harrelson
Found 2 solutions by Alan3354, scott8148:
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
2z%5E2+%2B+3z+=+135
2z%5E2+%2B+3z+-+135+=+0
(z + 9)*(2z - 15) = 0
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Either z+9 = 0 --> z = -9
Or 2z - 15 = 0 --> z = 15/2
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You can use the quadratic eqn, too. Does she know that?

Answer by scott8148(6628) About Me  (Show Source):
You can put this solution on YOUR website!
subtracting 135 ___ 2z^2 + 3z - 135 = 0

the object is to factor the quadratic into two binomials and then apply the zero product rule

finding two factors of -135, that can generate a sum of 3, when one of them is multiplied by 2

-15 and 9 are factors, 9 multiplied by 2 and added to -15 gives us 3

(2z - 15)(z + 9) = 0 ___ zero product states that if the product is zero, any or all of the factors are zero

2z - 15 = 0 ___ 2z = 15 ___ z = 15/2

z + 9 = 0 ___ z = -9