+0  
 
0
68
1
avatar+621 

Let \(f(x) = \left\{ \begin{array}{cl} 2x + 7 & \text{if } x < -2, \\ -x^2 - x + 1 & \text{if } x \ge -2. \end{array} \right.\)Find the sum of all values of x such that f(x)=-5.

mathtoo  Aug 28, 2018
 #1
avatar+90969 
+1

2x + 7  = -5      

2x  = -12

x = -6

 

-x^2 - x + 1    = -5     multiply through by -1

x^2 + x - 1  = 5

x^2 + x  - 6  = 0   factor

(x + 3) ( x - 2)  =  0

Set each factor to  0  and solve for  x and we get   x  = -3   (out of the domain for the function)  or  x = 2

 

So...the sum of the  x values such that f(x)   = -5  ⇒   -6  + 2   =  -4 

 

cool cool cool

CPhill  Aug 28, 2018

17 Online Users

New Privacy Policy

We use cookies to personalise content and advertisements and to analyse access to our website. Furthermore, our partners for online advertising receive information about your use of our website.
For more information: our cookie policy and privacy policy.