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For what values of $b$ is $-2$ not in the range of the function $f(x)=x^2+bx+2$? Express your answer in interval notation.

ignore the dollar signs. 

 Feb 12, 2019
 #1
avatar+19811 
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This was answered the other day.....

if the discriminant is less than zero it will not be a real number

 

x^2+bx+2 = -2

x^2+bx+4 = 0           discriminant is   b^2 - 4(ac)  =   b^2 - 4(1)(4)     if this is less than zero it will meet the requirements of your Q

b^2-16 <0

b^2 <16

b< +-4        so the interval is        (-4,4)

 Feb 12, 2019

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