vertex; axis of symmetry; Calculate the y-intercept; Use the axis of symmetry and the y-intercept to find an additional point on the graph; Graph the function please help. This is college algebra...

vertex;

axis of symmetry; Calculate the y-intercept; Use the axis of symmetry and the y-intercept to find an additional point on the graph; Graph the function

please help. This is college algebra not calculus. confuse

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embizze | High School Teacher | (Level 1) Educator Emeritus

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Given a quadratic function find: axis of symmetry, y-intercept. Use the axis of symmetry and the y-intercept to find an additional point on the graph then graph the function.

Let `y=ax^2+bx+c` e.g x^2+7x+12 (Here a=1,b=7,c=12)

(1) The axis of symmetry is the vertical line `x=-b/(2a)` . For the example `x=-7/2` .

(2) The y-intercept is where x=0, or c. For the example the y-intercept is 12.

(3) The line x=0 is 7/2 to the right of the axis of symmetry, so there is a point with y value of 12 when `x=-7/2-7/2=-7` . Thus there is a point (0,12) (the y-intercept) and a point (-7,12), a reflection of the intercept across the line of symmetry. (Imagine folding the paper along the line `x=-7/2` and pairing up points.)

(4) The graph is a "U" opening up (Since a>0). The example yields

** If the equation is given in another form there are other approaches. **

 

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