SOLUTION: I'm working on factoring trinomials, and I cannot find the answer to two problems. 1. x squared -4x+24 2. k squared -13k+40

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Question 579188: I'm working on factoring trinomials, and I cannot find the answer to two problems.
1. x squared -4x+24
2. k squared -13k+40

Answer by dfrazzetto(283) About Me  (Show Source):
You can put this solution on YOUR website!
1. x squared -4x+24


x^2 -4x + 24
Cannot be factored, (non-integer roots), verify w/ quadratic equation
Solved by pluggable solver: SOLVE quadratic equation with variable
Quadratic equation ax%5E2%2Bbx%2Bc=0 (in our case 1x%5E2%2B-4x%2B24+=+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=%28-4%29%5E2-4%2A1%2A24=-80.

The discriminant -80 is less than zero. That means that there are no solutions among real numbers.

If you are a student of advanced school algebra and are aware about imaginary numbers, read on.


In the field of imaginary numbers, the square root of -80 is + or - sqrt%28+80%29+=+8.94427190999916.

The solution is

Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+1%2Ax%5E2%2B-4%2Ax%2B24+%29



2. k squared -13k+40

Can be factored:
(k-5)(k-8) = k^2 -13k + 40 √
Solved by pluggable solver: SOLVE quadratic equation with variable
Quadratic equation ak%5E2%2Bbk%2Bc=0 (in our case 1k%5E2%2B-13k%2B40+=+0) has the following solutons:

k%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=%28-13%29%5E2-4%2A1%2A40=9.

Discriminant d=9 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28--13%2B-sqrt%28+9+%29%29%2F2%5Ca.

k%5B1%5D+=+%28-%28-13%29%2Bsqrt%28+9+%29%29%2F2%5C1+=+8
k%5B2%5D+=+%28-%28-13%29-sqrt%28+9+%29%29%2F2%5C1+=+5

Quadratic expression 1k%5E2%2B-13k%2B40 can be factored:
1k%5E2%2B-13k%2B40+=+1%28k-8%29%2A%28k-5%29
Again, the answer is: 8, 5. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+1%2Ax%5E2%2B-13%2Ax%2B40+%29