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Select the appropriate values of x that are solutions to f(x)=0, where f(x)=2x^2+2x+8

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2 Answers

Hi Valerie,
 
 
f(x)=0
 
f(x)=2x²+2x+8
 
2x²+2x+8=0
 
x²+x+4=0
 
By using the quadratic formula,
 
x = -1±√(1)²-4(1)(4)            
            2(1)
 
= -1±√-15
        2
 
=-1/2±i√15/2
2x2 + 2x + 8= 0
 
use the formula for solving a standard quadratic equation Ax2 + Bx + C = 0
 
 
x = (-B + √ (B2 - 4AC))/2A
 
In this question plug in A = 2, B =2 and C=8, if B2 - 4AC is negative or <0 the the solution of X would be comples number expressed in terms of i (√-1)
 
x= (-2 + √(4 - 4x2x8))/2x2
 
=> (-2 + √(-60))/4
 
x = -2/4  +  √60i/4
 
:)