SOLUTION: Do you know what would be the x intercepts of {{{ x^2-40x-500 }}} I have tried solving it but the answers I have gotten are 42.14 and -2.14 as well as 44.27.

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: Do you know what would be the x intercepts of {{{ x^2-40x-500 }}} I have tried solving it but the answers I have gotten are 42.14 and -2.14 as well as 44.27.      Log On


   

Question 718326: Do you know what would be the x intercepts of +x%5E2-40x-500+ I have tried solving it but the answers I have gotten are 42.14 and -2.14 as well as 44.27.
Answer by jsmallt9(3758) About Me  (Show Source):
You can put this solution on YOUR website!
The x-intercepts of y+=+x%5E2-40x-500 are where the graph intersects the x-axis. Since all points on the x-axis have a y-coordinate of 0, x-intercepts are found by replacing the y with zero and solving for x:
0+=+x%5E2-40x-500
This factors fairly easily:
0+=+%28x-50%29%28x%2B10%29
From the Zero Product Property:
x-50 = 0 or x+10 = 0
Solving these we get:
x = 50 or x = -10
The x-intercepts of y+=+x%5E2-40x-500 are (50, 0) and (-10, 0).

P.S. You get the same answers if you use the Quadratic Formula (or any other legitimate way) to solve 0+=+x%5E2-40x-500). I don't know how you came up with decimal answers. But if you used the Quadratic Formula, then you must have made a mistake somewhere (which is an argument for solving by factoring when possible). Here's the solution using the formula:
x+=+%28-%28-40%29+%2B-+sqrt%28%28-40%29%5E2-4%281%29%28-500%29%29%29%2F2%281%29
Simplifying...
x+=+%28-%28-40%29+%2B-+sqrt%281600-4%281%29%28-500%29%29%29%2F2%281%29
x+=+%28-%28-40%29+%2B-+sqrt%281600%2B2000%29%29%2F2%281%29
x+=+%28-%28-40%29+%2B-+sqrt%283600%29%29%2F2%281%29
x+=+%28-%28-40%29+%2B-++60%29%2F2%281%29
x+=+%2840+%2B-++60%29%2F2
which is short for:
x+=+%2840+%2B++60%29%2F2 or x+=+%2840+-++60%29%2F2
Simplifying...
x+=+100%2F2 or x+=+-20%2F2
x = 50 or x = -10