SOLUTION: question is: f(x)=2x^2-x-1 List the y-intercept, if there is one, of the graph of f(x).

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Question 40249This question is from textbook College Algebra
: question is: f(x)=2x^2-x-1
List the y-intercept, if there is one, of the graph of f(x). This question is from textbook College Algebra

Answer by Nate(3500) About Me  (Show Source):
You can put this solution on YOUR website!
f(x)=2x^2-x-1
The y-intercept is at -1 because when you fill in zero for the x, you get zero.
Solved by pluggable solver: SOLVE quadratic equation with variable
Quadratic equation ax%5E2%2Bbx%2Bc=0 (in our case 2x%5E2%2B-1x%2B-1+=+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=%28-1%29%5E2-4%2A2%2A-1=9.

Discriminant d=9 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28--1%2B-sqrt%28+9+%29%29%2F2%5Ca.

x%5B1%5D+=+%28-%28-1%29%2Bsqrt%28+9+%29%29%2F2%5C2+=+1
x%5B2%5D+=+%28-%28-1%29-sqrt%28+9+%29%29%2F2%5C2+=+-0.5

Quadratic expression 2x%5E2%2B-1x%2B-1 can be factored:
2x%5E2%2B-1x%2B-1+=+2%28x-1%29%2A%28x--0.5%29
Again, the answer is: 1, -0.5. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+2%2Ax%5E2%2B-1%2Ax%2B-1+%29