+0  
 
-1
39
1
avatar+1847 

One root of the quadratic equation $x^2 + bx -28 = 4x + 14$ is $-7$.   What is the value of $b$?

 Aug 23, 2023
 #1
avatar+36923 
+1

If  - 7  is a root....putting in  -7   for 'x'   will result in the equation = 0       Putting all of the factors on the LEFT side:

 

x^2 + x ( b-4) -42 = 0 

(-7)^2 + (-7) (b-4) - 42 = 0 

49 - 7b + 28 - 42 = 0

35 = 7b 

b = 5 

 Aug 23, 2023

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