SOLUTION: 1. x^2 + 2x -15 = 0 2. 4x^2 + 32x +15 = 0 3. -2x^2 + x +1 = 0 4. 2x^2 +7x + 0 5. -2x^2 +110x + 9 = 0

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: 1. x^2 + 2x -15 = 0 2. 4x^2 + 32x +15 = 0 3. -2x^2 + x +1 = 0 4. 2x^2 +7x + 0 5. -2x^2 +110x + 9 = 0      Log On


   

Question 798306: 1. x^2 + 2x -15 = 0
2. 4x^2 + 32x +15 = 0
3. -2x^2 + x +1 = 0
4. 2x^2 +7x + 0
5. -2x^2 +110x + 9 = 0
Found 2 solutions by harpazo, Alan3354:
Answer by harpazo(655) About Me  (Show Source):
You can put this solution on YOUR website!
Five questions?
Where is your effort?

Use the quadratic formula below for all 5 trinomials in the form ax^2+bx+c.

x = [-b+-sqrt{b^2-4ac}]/2a

Show your work.

Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
1. x^2 + 2x -15 = 0
2. 4x^2 + 32x +15 = 0
3. -2x^2 + x +1 = 0
4. 2x^2 +7x + 0
5. -2x^2 +110x + 9 = 0
--------------
I'll do #5
Solved by pluggable solver: SOLVE quadratic equation (work shown, graph etc)
Quadratic equation ax%5E2%2Bbx%2Bc=0 (in our case -2x%5E2%2B110x%2B9+=+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=%28110%29%5E2-4%2A-2%2A9=12172.

Discriminant d=12172 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28-110%2B-sqrt%28+12172+%29%29%2F2%5Ca.

x%5B1%5D+=+%28-%28110%29%2Bsqrt%28+12172+%29%29%2F2%5C-2+=+-0.0816968296006024
x%5B2%5D+=+%28-%28110%29-sqrt%28+12172+%29%29%2F2%5C-2+=+55.0816968296006

Quadratic expression -2x%5E2%2B110x%2B9 can be factored:
-2x%5E2%2B110x%2B9+=+%28x--0.0816968296006024%29%2A%28x-55.0816968296006%29
Again, the answer is: -0.0816968296006024, 55.0816968296006. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+-2%2Ax%5E2%2B110%2Ax%2B9+%29

===========
#1 - 4 can be factored.