Quadratic in standard form help please

  • #1
Quadratic in standard form help....please

Homework Statement



Write the quadratic function f(x) = x^2 + 3x + 2 in standard form.

Homework Equations



Standard form equation : f(x) = a(x-h)^2 + k


The Attempt at a Solution



Ok, I think I got this one but am wanting to be sure.

I set it up : (x^2 + 3x + 2.25) + 2

then get : (x + 1.5)^2 + 2 - 2.25

then get as answer : f(x) = (x + 1.5)^2 - .25

Is this what you all get ? :smile:

I really appreciate any help.
 

Answers and Replies

  • #2
2,063
2
Where did the 2.25 come from?
 
  • #3
cristo
Staff Emeritus
Science Advisor
8,107
73

Homework Statement



Write the quadratic function f(x) = x^2 + 3x + 2 in standard form.

Homework Equations



Standard form equation : f(x) = a(x-h)^2 + k


The Attempt at a Solution



Ok, I think I got this one but am wanting to be sure.

I set it up : (x^2 + 3x + 2.25) + 2

then get : (x + 1.5)^2 + 2 - 2.25

then get as answer : f(x) = (x + 1.5)^2 - .25

Is this what you all get ? :smile:

I really appreciate any help.
That looks fine to me. If you want to check in future, expand out the bracket, and simplify. What you get should be equal to the original expression.

Edit: I didn't read any lines other than the last one! The final answer is correct, however the method doesn't make much sense (I'm glad someone's on the ball, neutrino! :smile: )
 
Last edited:
  • #5
Thanks cristo ! I am checking it now. It works out :) Thanks for the tip.
 
Last edited:
  • #6
2,063
2
Take half of three and multiply it by itself.
Okay, but it can't magically appear from nowhere, can it? :wink: You add and subtract that amount, so that the expression x^2+3x+2 +2.25 -2.25 is equivalent to x^2+3x+2.
 

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