Math Problem Statement
Given Q(x) = ax^3 - bx^2 - cx + 6. If (x + 2) is a factor of Q(x) and Q(x) passes through the points (-1,10) and (2,4), find the values of a, b and c. Hence, factorise Q(x) completely
Solution
Given the polynomial , we are provided with the following information:
- is a factor of .
- passes through the points and .
Step 1: Use the fact that is a factor.
Since is a factor of , by the Factor Theorem, we know: Substitute into the polynomial: This simplifies to:
Step 2: Use the fact that .
Substitute into the polynomial: This simplifies to:
Step 3: Use the fact that .
Substitute into the polynomial: This simplifies to:
Step 4: Solve the system of equations.
We now have the following system of linear equations:
Step 4.1: Simplify the equations:
Equation 1:
Dividing by 2:
Equation 3:
Dividing by 2:
Step 4.2: Add the simplified Equation 1 and Equation 3:
Simplifying gives:
Step 4.3: Substitute into Equation 2:
So, .
Step 4.4: Substitute and into the simplified Equation 1:
Simplifying gives: This simplifies to:
Now, substitute back into the equations to find :
Thus, the values are:
Step 5: Factorize completely.
Substitute , , and into the original polynomial:
Given is a factor:
Now, factorize the quadratic : The quadratic can be factorized as:
Thus, the complete factorization of is:
Final Answer:
- Values: , ,
- Factorization:
Would you like a more detailed explanation on any step? Here are some related questions:
- How do you apply the Factor Theorem to factorize polynomials?
- What are the steps to solve a system of linear equations?
- How can you verify the factorization of a cubic polynomial?
- What techniques are there for factoring quadratic equations?
- How do transformations affect the graph of a polynomial function?
Tip: When factorizing polynomials, always check if simpler factors (like binomials) can be factored out first before attempting more complex methods.
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Math Problem Analysis
Mathematical Concepts
Polynomials
Factorization
Quadratic Equations
System of Equations
Formulas
Factor Theorem
Theorems
Factor Theorem
Suitable Grade Level
Grades 10-12