Equation of the quadratic function

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Albi

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How can I find the equation of this quadratic function [imath]y= ax^{2} + 2x + c[/imath] if I know two points (-2,0) , (3,5) and the value of b which is 2.
 
Albi said:
How can I find the equation of this quadratic function [imath]y= ax^{2} + 2x + c[/imath] if I know two points (-2,0) , (3,5) and the value of b which is 2.
Click to expand...
y = a * x^2 + 2x + c​
​
Now use the given two points to solve for two unknowns ( a & c).​

Please show us what you have tried and exactly where you are stuck.

Please follow the rules of posting in this forum, as enunciated at:


Please share your work/thoughts about this problem.
 
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Albi said:
How can I find the [values of a and c in] this quadratic function y=ax^2+2x+c if I know two points (-2,0) , (3,5)
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Hi Albi. You can subtitute the given (x,y) values and simplify, to obtain two new equations. Solve that system of two equations for a and c.

Then check your results, by verifying that x=-2 gives y=0 AND x=3 gives y=5.

Please share your efforts. Thank you!

?
 
Otis said:
Hi Albi. You can subtitute the given (x,y) values and simplify, to obtain two new equations. Solve that system of two equations for a and c.

Then check your results, by verifying that x=-2 gives y=0 AND x=3 gives y=5.

Please share your efforts. Thank you!

?
Click to expand...
I got two equations [imath]4a +c =0[/imath] and [imath]9a+c= 5[/imath] , I added them up and I got a = 1 and c = -4, but that's not the correct answer since one of the zeros of this equation is -2 but when I substitute a and c into the equation I get [imath]x_{1}= -1-\sqrt{5}[/imath] and [math]x_{2}=-1+ \sqrt{5}[/math]
 
Otis said:
Those are close, but not correct. Please show your work.

?
Click to expand...
Here it is, even though it's incorrect.
I don't know what I am missing
 

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Albi said:
Here it is, even though it's incorrect.
I don't know what I am missing
Click to expand...
Your equations are incorrect - after putting in values of x & y.

Try from the very beginning again​
 
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