SOLUTION: solve 2x^2 - 3x - 2 = 0 using quadratic formula

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Question 200226: solve
2x^2 - 3x - 2 = 0 using quadratic formula

Answer by Edwin McCravy(20055) About Me  (Show Source):
You can put this solution on YOUR website!
solve
2x%5E2+-+3x+-+2+=+0 using quadratic formula

It could be solved easier by factoring like this:

2x%5E2+-+3x+-+2+=+0

%28x-2%29%282x%2B1%29=0

x-2=0 or x=2

2x%2B1=0 or 2x=-1 or x=-1%2F2

But you are told specifically to do it by the
quadratic formula.  So this is what we do
there:

The solution to

ax%5E2%2Bbx%2Bc=0 is

x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+

You must memorize that!

In your problem

2x%5E2+-+3x+-+2+=+0

a=2, b=-3, c=-2

So substituting:

x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+



x+=+%283+%2B-+sqrt%28+9%2B16+%29%29%2F4+

x+=+%283+%2B-+sqrt%2825%29%29%2F4+

x+=+%283+%2B-+5%29%2F4+

That's two solutions

1.   x+=+%283+%2B+5%29%2F4+=+8%2F4+=+2

2.   x+=+%283+-+5%29%2F4+=+-2%2F4+=+-1%2F2

So you see we get the same solutions as we did 
when we factored it.

Edwin