Find Coefficients in the Equation y=4+3x-x²: Term-by-Term Analysis

Quadratic Functions with Standard Form Conversion

Identify the coefficients based on the following equation

y=4+3xx2 y=4+3x-x^2

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:06 Let's find the function coefficients.
00:10 We'll use the formula for a quadratic equation.
00:16 Now, let's arrange the equation to match that formula.
00:36 Next, we'll separate the variable from its coefficient.
00:49 We'll compare our equation with the formula to find the coefficients.
01:03 And that's how we solve the question.

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=4+3xx2 y=4+3x-x^2

2

Step-by-step solution

To solve this problem, we'll follow these steps:

  • Step 1: Identify the standard form of a quadratic function y=ax2+bx+c y = ax^2 + bx + c .
  • Step 2: Rearrange the given function y=4+3xx2 y = 4 + 3x - x^2 to match the standard form.
  • Step 3: Compare the terms and determine the values of a a , b b , and c c .

Now, let's work through these steps:

Step 1: The standard form of a quadratic equation is y=ax2+bx+c y = ax^2 + bx + c .

Step 2: The provided function is written as y=4+3xx2 y = 4 + 3x - x^2 . We can rearrange this in descending order of x x to become y=x2+3x+4 y = -x^2 + 3x + 4 , which aligns more closely with the standard form.

Step 3: By comparing the rearranged equation y=x2+3x+4 y = -x^2 + 3x + 4 with the standard form y=ax2+bx+c y = ax^2 + bx + c , we can determine:

  • The coefficient of x2 x^2 is 1-1, hence a=1 a = -1 .
  • The coefficient of x x is 33, thus b=3 b = 3 .
  • The constant term is 44, so c=4 c = 4 .

Therefore, the values of a a , b b , and c c are a=1 a = -1 , b=3 b = 3 , and c=4 c = 4 .

3

Final Answer

a=1,b=3,c=4 a=-1,b=3,c=4

Key Points to Remember

Essential concepts to master this topic
  • Standard Form: Always rearrange as y=ax2+bx+c y = ax^2 + bx + c with descending powers
  • Technique: Rewrite y=4+3xx2 y = 4 + 3x - x^2 as y=x2+3x+4 y = -x^2 + 3x + 4
  • Check: Verify coefficient of x2 x^2 is a=1 a = -1 , not positive ✓

Common Mistakes

Avoid these frequent errors
  • Forgetting the negative sign in the x² coefficient
    Don't identify the coefficient of x2 -x^2 as positive 1 = wrong answer! The minus sign is part of the coefficient, making it -1. Always include the sign when identifying coefficients in quadratic functions.

Practice Quiz

Test your knowledge with interactive questions

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

\( 4x^2+9x-2 \)

FAQ

Everything you need to know about this question

Why do we need to rearrange the equation first?

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Rearranging helps you match the standard form y=ax2+bx+c y = ax^2 + bx + c exactly. When terms are in different order like y=4+3xx2 y = 4 + 3x - x^2 , it's harder to identify which coefficient is which.

What if there's no x² term in the equation?

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If there's no x2 x^2 term, then a = 0 and you have a linear equation, not a quadratic! The equation would be y=bx+c y = bx + c instead.

How do I remember which coefficient is a, b, or c?

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Think of alphabetical order matching power order: a goes with x2 x^2 (highest power), b goes with x1 x^1 (middle power), and c is the constant (no x).

What does the negative coefficient mean for the graph?

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When a is negative (like our a=1 a = -1 ), the parabola opens downward like an upside-down U. Positive a values make parabolas open upward.

Can I just read the coefficients without rearranging?

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It's risky! While possible, rearranging to standard form y=ax2+bx+c y = ax^2 + bx + c helps you avoid mistakes and makes coefficient identification foolproof.

What if a term is missing like no bx term?

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

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