SOLUTION: what is y=X2+4x-9?

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Question 73413This question is from textbook Algebra 1
: what is y=X2+4x-9? This question is from textbook Algebra 1

Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
If you're looking to solve for x then let y=0 and use the quadratic equation
Solved by pluggable solver: SOLVE quadratic equation with variable
Quadratic equation ax%5E2%2Bbx%2Bc=0 (in our case 1x%5E2%2B4x%2B-9+=+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=%284%29%5E2-4%2A1%2A-9=52.

Discriminant d=52 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28-4%2B-sqrt%28+52+%29%29%2F2%5Ca.

x%5B1%5D+=+%28-%284%29%2Bsqrt%28+52+%29%29%2F2%5C1+=+1.60555127546399
x%5B2%5D+=+%28-%284%29-sqrt%28+52+%29%29%2F2%5C1+=+-5.60555127546399

Quadratic expression 1x%5E2%2B4x%2B-9 can be factored:
1x%5E2%2B4x%2B-9+=+1%28x-1.60555127546399%29%2A%28x--5.60555127546399%29
Again, the answer is: 1.60555127546399, -5.60555127546399. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+1%2Ax%5E2%2B4%2Ax%2B-9+%29