SOLUTION: Please help me answer this. solve each equation by using the quadratic formula 1.) 3x^2+x-4=0

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Question 487465: Please help me answer this.
solve each equation by using the quadratic formula
1.) 3x^2+x-4=0

Answer by Edwin McCravy(20054) About Me  (Show Source):
You can put this solution on YOUR website!
This problem could be done by factoring

3x² +  x - 4 = 0
 (3x+4)(x-1) = 0

3x+4= 0;  x-1=0
  3x=-4     x=1
   x=-4%2F3

But you are to use the quadratic formula:

3x² +  x - 4 = 0   <--- take your problem and 

3x² + 1x - 4 = 0   <--- compare it to 

ax² + bx + c = 0   <--- this 

a = 3, b = 1, c = -4 which we substitute into:   


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

 x+=+%28-%281%29+%2B-+sqrt%28%281%29%5E2-4%2A%283%29%2A%28-4%29+%29%29%2F%282%2A%283%29%29+

 x+=+%28-1+%2B-+sqrt%281%2B48%29%29%2F6+

 x+=+%28-1+%2B-+sqrt%2849%29%29%2F6+

 x+=+%28-1+%2B-+7%29%2F6+

That breaks into two solutions:

 x+=+%28-1+%2B+7%29%2F6+  and  x+=+%28-1+-+7%29%2F6+

Simplifying the first one:

 x+=+%28-1+%2B+7%29%2F6+
 x+=+6%2F6+
 x+=+1

Simplifying the second one:

 x+=+%28-1+-+7%29%2F6+
 x+=+-8%2F6+
 x+=+-4%2F3

So the solutions are 1 and -4%2F3, the same
as when we solved it by factoring.  The reason we
have to use the quadratic formula is because most
quadratic equations will not factor.

Edwin