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The expression 2z^2+13z+21 can be written as (z+a)(2z+b), where a and bare integers. What is 2a+b?

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 Apr 21, 2020
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The expression 2z^2+13z+21 can be written as (z+a)(2z+b), where a and bare integers. What is 2a+b? 

 

The standard construction is ax2 + bx + c  so in the example, a is 2, b is 13, and c is 21 

Going by this, (2 • 2) + 13 = 17 but I don't think that's what the question is asking for.

 

Actually, 2z2 + 13z + 21 factors to (z + 3)(2z + 7) 

so I guess you are looking for (2 • 3) + 7  = 13 

 

.

 Apr 21, 2020

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