Find Coefficients in the Equation y=3-x-x²: Step-by-Step Guide

Quadratic Coefficients with Standard Form

Identify the coefficients based on the following equation

y=3xx2 y=3-x-x^2

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:07 Let's find the numbers in front of the terms in the function.
00:11 We use a formula to show a quadratic equation.
00:17 First, arrange your equation so it looks like the formula.
00:39 Next, separate the variables from the numbers in front.
00:52 Now compare your equation to the formula and find the numbers, called coefficients.
01:01 And that's how we solve this problem!

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Identify the coefficients based on the following equation

y=3xx2 y=3-x-x^2

2

Step-by-step solution

To solve this problem, we need to compare the given quadratic function with the standard form.

The given function is y=3xx2 y = 3 - x - x^2 . We can rearrange this into the standard quadratic form:

y=x2x+3 y = -x^2 - x + 3 .

In the standard quadratic form, y=ax2+bx+c y = ax^2 + bx + c , we identify the coefficients:

  • The coefficient of x2 x^2 is a=1 a = -1 .
  • The coefficient of x x is b=1 b = -1 .
  • The constant term is c=3 c = 3 .

Therefore, based on the standard quadratic form, the parameters are a=1 a = -1 , b=1 b = -1 , and c=3 c = 3 .

We match these coefficients to the given multiple-choice answers.

Therefore, the correct answer choice is:
a=1,b=1,c=3 a = -1, b = -1, c = 3 .

3

Final Answer

a=1,b=1,c=3 a=-1,b=-1,c=3

Key Points to Remember

Essential concepts to master this topic
  • Standard Form: Always write quadratic equations as ax2+bx+c ax^2 + bx + c
  • Rearrange: Change 3xx2 3 - x - x^2 to x2x+3 -x^2 - x + 3
  • Check: Verify coefficients: a=1 a = -1 , b=1 b = -1 , c=3 c = 3

Common Mistakes

Avoid these frequent errors
  • Reading coefficients from original order
    Don't read coefficients directly from y=3xx2 y = 3 - x - x^2 as a = 3, b = -1, c = -1! This ignores the standard form requirement and gives wrong coefficient assignments. Always rearrange to ax2+bx+c ax^2 + bx + c first, then identify coefficients.

Practice Quiz

Test your knowledge with interactive questions

What is the value of the coefficient \( b \) in the equation below?

\( 3x^2+8x-5 \)

FAQ

Everything you need to know about this question

Why can't I just read the coefficients from left to right?

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Coefficients must be identified from the standard form ax2+bx+c ax^2 + bx + c . The original equation y=3xx2 y = 3 - x - x^2 isn't in standard order, so you need to rearrange it first!

How do I rearrange the equation correctly?

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Start with y=3xx2 y = 3 - x - x^2 and rewrite in descending powers: highest degree first. This gives you y=x2x+3 y = -x^2 - x + 3 .

What if the x² term is negative like in this problem?

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That's perfectly normal! The coefficient a can be positive or negative. Here, a=1 a = -1 because we have x2 -x^2 , which means 1x2 -1 \cdot x^2 .

How do I remember which coefficient is which?

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Use the pattern ax2+bx+c ax^2 + bx + c :

  • a = coefficient of x2 x^2
  • b = coefficient of x x
  • c = constant term (no variable)

What if there's no x term or constant term?

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If a term is missing, its coefficient is 0. For example, y=2x2+5 y = 2x^2 + 5 has a=2 a = 2 , b=0 b = 0 , c=5 c = 5 .

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