SOLUTION: Hi, I am so lost on this problem I don't know how to do this problem please help! Using the Quadratic Formula, which of the following is the solution to the quadratic equatio

Algebra ->  Equations -> SOLUTION: Hi, I am so lost on this problem I don't know how to do this problem please help! Using the Quadratic Formula, which of the following is the solution to the quadratic equatio      Log On


   

Question 901008: Hi,
I am so lost on this problem I don't know how to do this problem please help!
Using the Quadratic Formula, which of the following is the solution to the quadratic equation x2 + 2x – 25 = 0?
a.x=-1-v5,x=-1+v5
b.x=-1-v26,x=-1+v26
c.x=-1-v104,x=1+v104
d.x=-1-v26,x=-1+v26
Found 2 solutions by ewatrrr, Alan3354:
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
 

Hi

1x^2 + 2x – 25 = 0   |Format ax^2 + bx + c

x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+  |Substitute: a = 1, b = 2, c = -25

x+=+%28-2+%2B-+sqrt%28+4%2B+100+%29%29%2F%282%29+  |Follow thru to the finish!

x+=+%28-2+%2B-+sqrt%28+104+%29%29%2F%282%29+

x+=+%28-2+%2B-+sqrt%284%2A26+%29%29%2F%282%29+

x+=+%28-2+%2B-+2sqrt%2826+%29%29%2F%282%29+

x+=+-1+%2B-+sqrt%2826%29

Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
Using the Quadratic Formula, which of the following is the solution to the quadratic equation x2 + 2x – 25 = 0
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Solved by pluggable solver: SOLVE quadratic equation (work shown, graph etc)
Quadratic equation ax%5E2%2Bbx%2Bc=0 (in our case 1x%5E2%2B2x%2B-25+=+0) has the following solutons:

x%5B12%5D+=+%28b%2B-sqrt%28+b%5E2-4ac+%29%29%2F2%5Ca

For these solutions to exist, the discriminant b%5E2-4ac should not be a negative number.

First, we need to compute the discriminant b%5E2-4ac: b%5E2-4ac=%282%29%5E2-4%2A1%2A-25=104.

Discriminant d=104 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28-2%2B-sqrt%28+104+%29%29%2F2%5Ca.

x%5B1%5D+=+%28-%282%29%2Bsqrt%28+104+%29%29%2F2%5C1+=+4.09901951359278
x%5B2%5D+=+%28-%282%29-sqrt%28+104+%29%29%2F2%5C1+=+-6.09901951359278

Quadratic expression 1x%5E2%2B2x%2B-25 can be factored:
1x%5E2%2B2x%2B-25+=+%28x-4.09901951359278%29%2A%28x--6.09901951359278%29
Again, the answer is: 4.09901951359278, -6.09901951359278. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+1%2Ax%5E2%2B2%2Ax%2B-25+%29

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