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\(\text{If $f(x)=\frac{x+4}{x^2+ax+b}$, and $f(x)$ has two vertical asymptotes at $x=1$ and $x=-2$, find the sum of $a$ and $b$. }\)

 

Thanks in advance!laugh

 Jul 15, 2019
 #1
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+2

                          x + 4    

f(x)    =      ___________

                   x^2 + ax + b

 

If we have vertical asymptotes  at  x  = 1  and  x  = -2  then the denominator  is  ( x - 1) ( x + 2)

 

So.....the denominator  becomes  x^2 - 1x + 2x - 2  =   x^2 + 1x  - 2

 

So     a  =  1   and b =  - 2

 

And their sum is   - 1

 

 

cool cool cool

 Jul 15, 2019

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