Hannah H.

asked • 10/13/16

Intersections with quadratic

Look at the two quadratic equations below.
y=3x^2-x+7
y=x^2+4x+14
how many times will the graphs of these functions intersect?
determine the points of the intersection

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Mark M. answered • 10/13/16

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Two intersections
3x2 - x + 7 = x2 + 4x + 14
2x2 - 5x - 7 = 0
(x + 1)(2x - 7) = 0
 
What are the coordinates of the intersections?
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Hannah H.

How do I find the points of intersection? 
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10/17/16

Mark M.

What are the solutions (x-values) to the last equation?
Substitute these values into either of the original equation to determine the y-values.
 
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10/17/16

Hannah H.

Okay. i understand that the first intersection is (-1,11). I know that because I got I already solved for x with the factoring you provided me with [(x+1)(2x-7)]. but if you solve the second one- the x value ends up being 3.5. when you solve for y- the answer doesnt make sense because it ends up being 40.25- which is a very high x value. i put the two equations in my graphing calculator and the two intersections are (-1,11) and (0,14). Help?
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10/17/16

Hannah H.

actually never mind. they didnt intersect at (0,14). Thank you for your help!!!
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10/17/16

Mark M.

Good job! You are welcome.
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10/17/16

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