Question 29242: 0 = 5(x^3) + 10 + 10(x^2)
solve for x? or factor?
Answer by sdmmadam@yahoo.com(530)   (Show Source):
You can put this solution on YOUR website! 0 = 5(x^3) + 10 + 10(x^2)
solve for x? or factor?
The problem should have been
0= 5(x^3) + 10x + 10(x^2)
That is 5(x^3) + 10x + 10(x^2) = 0
5x(x^2+2+2x)=0
Dividing by 5
x(x^2+2x+2) =0
x=0 or
(x^2+2x+2) =0
(x^2+2x+1)+1 =0
(x+1)^2 +1=0
(x+1)^2 = -1
(x+1)^2 =(i^2)
(x+1)= + or (-)(i)
x= [-1 + or (-)(i)]
That is x= (-1+i) and x= (-1-i)
Answer:x=0, x= (-1+i) and x= (-1-i)
Note: (x^2+2x+2) =0
[using formula: if Ax^2+Bx+C=0 then x ={-b+ or -[sqrt(b^2-4ac)]}/2a
x= {-2 + or - sqrt[4-4X1X2]}/(2X1)
=[-2 + or - sqrt(-4)]/2
=[-2 + or (-)(2i)]/2 = [-1+or(-)(i)](canceling 2)
Answer: x=0, x= (-1+i) and x= (-1-i)
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