SOLUTION: In a quadratic equation-standard, vertex, and factored form-how do you calculate the 'a'? ex: I know part of the equation of a parabola- y=a(x+7)(x+3). so what's 'a'?

Question 440477: In a quadratic equation-standard, vertex, and factored form-how do you calculate the 'a'?
ex: I know part of the equation of a parabola- y=a(x+7)(x+3). so what's 'a'?
Found 2 solutions by richard1234, lwsshak3:
Answer by richard1234(7193) (Show Source): You can put this solution on YOUR website!
If you are given an initial constraint (e.g. the parabola passes through a certain point), then replace the x- and y-values of that point and solve for a. Otherwise, you can assume a is any non-zero constant.
Answer by lwsshak3(11628) (Show Source): You can put this solution on YOUR website!
In a quadratic equation-standard, vertex, and factored form-how do you calculate the 'a'?
ex: I know part of the equation of a parabola- y=a(x+7)(x+3). so what's 'a'?
..
All you need is one point on the curve to find a. Just plug in x and y and solve for a.
The coefficient "a" affects the steepness of the parabola, that is, the higher it is, the steeper or narrower the parabola. You can easily show this on a graphing calculator.
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