Equation of the quadratic function

[Albi]

How can I find the equation of this quadratic function $y= ax^{2} + 2x + c$ if I know two points (-2,0) , (3,5) and the value of b which is 2.

 

[Deleted member 4993]

How can I find the equation of this quadratic function $y= ax^{2} + 2x + c$ if I know two points (-2,0) , (3,5) and the value of b which is 2.

y = a * x^2 + 2x + c​

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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:

READ BEFORE POSTING​

Please share your work/thoughts about this problem.

 

[Otis]

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)

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!

?

 

[Albi]

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!

?

I got two equations $4a +c =0$ and $9a+c= 5$ , 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 $x_{1}= -1-\sqrt{5}$ and $$x_{2}=-1+ \sqrt{5}$$

 

[Otis]

I got two equations 4a + c = 0 and 9a + c = 5

Those are close, but not correct. Please show your work.

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[Albi]

Those are close, but not correct. Please show your work.

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

 

[Deleted member 4993]

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

Your equations are incorrect - after putting in values of x & y.

Try from the very beginning again​

 

[Otis]

I don't know what I am missing

y = ax^2 + 2x + c

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[Albi]

y = ax^2 + 2x + c

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Now I did it correctly ?