In Exercises 1–30, factor each trinomial, or state that the trinomial is prime. Check each factorization using FOIL multiplication.x² + 9x + 20
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Identify the trinomial in the form \( ax^2 + bx + c \), where \( a = 1 \), \( b = 9 \), and \( c = 20 \).
Look for two numbers that multiply to \( c = 20 \) and add up to \( b = 9 \).
The numbers 4 and 5 multiply to 20 and add up to 9.
Rewrite the trinomial as \( (x + 4)(x + 5) \).
Verify the factorization by using the FOIL method: \( (x + 4)(x + 5) = x^2 + 5x + 4x + 20 = x^2 + 9x + 20 \).
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Factoring Trinomials
Factoring trinomials involves rewriting a quadratic expression in the form ax² + bx + c as a product of two binomials. The goal is to find two numbers that multiply to 'c' (the constant term) and add to 'b' (the coefficient of the linear term). This process simplifies solving quadratic equations and helps in graphing parabolas.
A trinomial is considered prime if it cannot be factored into the product of two binomials with real coefficients. This occurs when there are no two numbers that satisfy the conditions of multiplication and addition required for factoring. Recognizing prime trinomials is essential for determining the factorability of quadratic expressions.
The FOIL method is a technique used to multiply two binomials, standing for First, Outside, Inside, Last, which refers to the order in which the terms are multiplied. This method helps verify the correctness of a factorization by ensuring that the product of the binomials returns to the original trinomial. Understanding FOIL is crucial for checking work in factoring problems.