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f(x)=x^2+xfind even or odd or neither even nor oddand draw it's graph

tito

by tito at December 13, 2009

please help me

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First, plug -x into the function to see if you get the same function or the negative of it:f(-x) = (-x)^2 + (-x)        = x^2 - x Since this is not f(x) and it's not -f(x) = -(x^2) -x, the function is neither even nor odd.To graph it find the zeros:  f(x) = x(x+1), the zeros are x = 0 and -1. And the vertex of the parabola is at x = -1/2.  (because of the -b/2a rule).  So when x = -1/2, y = -1/2*(1/2) = -1/4.So plot (-1/2, -1/4), (-1, 0), and (0, 0), and then connect in a parabola shape. :-)A brightstorm video you can watch about even and odd functions that might make it clearer:http://www.brightstorm.com/d/math/s/precalculus/u/introduction-to-functions/t/symmetry-of-graphs-odd-and-even-functionsAnd another video in case graphing the parabola was confusing:http://www.brightstorm.com/d/math/s/algebra-2/u/quadratic-equations-and-inequalities/t/finding-the-vertex-of-a-parabola-by-completing-the...

Alison037 Alison037 December 13, 2009

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Tito - (1) A function is even if it is symmetric with the y-axis.  So it doesn't matter if x is positive or negative, you will always get the same y-value.  The best example is a parabola where f(x) = x^2.  Try plugging in some values for x and -x and convince yourself that f(x) = f(-x).  Does this work with your function?  If so, it is even. (2) A function is odd if it is symmetric with the origin.  The best example of this is a cubic where f(x) = x^3.  For odd functions, f(-x) = -f(x).  So in this example, when x=4, the cubic equals 4^3 or 64.  But, when x = -4, the cubic equals (-4)^3 or -64.  Does this work with your function?  If so, it is odd. So is f(x) = x^2 +x even, odd or neither?  Try testing it by following the steps in (1) and (2) above.  Use a graphing calculator and see if the function is symmetric with the y-axis, the origin or neither. Hope this helps

Steve204 Steve204 December 13, 2009

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