Question

Solve x2 + 4x + 8 = 0.

Answer 1

x equals negative 2 plus or minus 2 I

x equals negative 2 plus or minus 4 I

x equals negative 4 plus or minus 2 I

x equals negative 4 plus or minus 4 I

Answer 2

lets get this right, make sure you understand
go step by step
\[x^2+4x+8=0\] step one
subtract \(8\) from both sides
what do you get ?

Answer 3

@satellite73 don't you think that the quadratic formula would be easier than completing the square for someone who is not proficient at factoring?

Answer 4

no

Answer 5

x2+4x=0 ? @satellite73

Answer 6

ahh...difference of opinion then. My students in Algebra 2 hated completing the square once they knew the quadratic formula!

Answer 7

a) the middle term is \(4x\) and 4 is even
there will be no denominator
the quadratic formula forces a denominator on you then you have a raft more algebra to do

Answer 8

b) most people can't remember the formula correctly

Answer 9

c) almost no one can do the arithmetic right

Answer 10

x equals negative 2 plus or minus 2 I

x equals negative 2 plus or minus 4 I

x equals negative 4 plus or minus 2 I

x equals negative 4 plus or minus 4 I

Answer 11

but understanding competing the square is so much more difficult for students. And who's to say they will remember completing the square? Especially when you factor out a number to make the coefficient on the x^2 a 1.

Answer 12

@brangetsbuckets no it is not
\[x^2+4x=0\] if you start with
\[x^2+4x+8=0\] the \(8\) cannot disappear
subtract \(8\) from both sides

Answer 13

But you're a brillliant mind and I bow to your brains. I can see it both ways personallly; I enjoy completing the square so much more, but my students hate it.

Answer 14

@IMStuck thanks for the compliment
i guess i should have said in a case like this it is much easier to complete the square
if you had \(7x^2+5x-2=0\) the no it would not be

Answer 15

you are welcome...I meant it with total sincerity. Go on with your helping; I'll butt out now! ; )

Answer 16

im still lost @satellite73