+0  
 
0
30
1
avatar

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

 Aug 31, 2023

Best Answer 

 #1
avatar+36915 
+1

x^2 + bx -28 = 4x + 14    Simplify to 

x^2 + (b-4) x - 42 = 0             If - 7 is a root, puting in -7 for 'x' will result in this equation = 0 

(-7)^2 + (b-4)(-7) - 42 = 0 

49     - 7b + 28 - 42  = 0 

35 - 7b = 0

b = 5 

 Aug 31, 2023
 #1
avatar+36915 
+1
Best Answer

x^2 + bx -28 = 4x + 14    Simplify to 

x^2 + (b-4) x - 42 = 0             If - 7 is a root, puting in -7 for 'x' will result in this equation = 0 

(-7)^2 + (b-4)(-7) - 42 = 0 

49     - 7b + 28 - 42  = 0 

35 - 7b = 0

b = 5 

ElectricPavlov Aug 31, 2023

1 Online Users

avatar