Q. Rewrite the expression as a product of four linear factors:(4x2+15x)2+20(4x2+15x)+99Answer:
Recognize perfect square trinomial: Recognize the given expression as a perfect square trinomial. The expression is in the form of (A2+2AB+B2), where A=(4x2+15x) and B is a number we need to find such that B2=99 and 2AB=20(4x2+15x).
Find value of B: Find the value of B. We know that B2=99, so B is the square root of 99. Since 99 is not a perfect square, we can simplify it to B=9×11=311.
Verify 2AB matches: Verify that 2AB matches the middle term of the original expression.2AB=2×(4x2+15x)×311=20(4x2+15x) after simplifying.This matches the middle term of the original expression, confirming that B=311 is correct.
Write as perfect square: Write the expression as a perfect square.The original expression can now be written as a perfect square: [(4x2+15x)+311]2.
Factor binomial squared: Factor the perfect square as a binomial squared.The expression [(4x2+15x)+311]2 is the square of the binomial (4x2+15x+311).
Factor quadratic term: Factor the quadratic term within the binomial.To factor 4x2+15x+311, we look for two numbers that multiply to 4⋅311 and add to 15. However, this is not possible with integers, so we need to use the quadratic formula to find the roots of 4x2+15x+311=0.
Apply quadratic formula: Apply the quadratic formula to find the roots.The quadratic formula is x=2a−b±b2−4ac, where a=4, b=15, and c=311.
Calculate discriminant: Calculate the discriminant b2−4ac. The discriminant is 152−4⋅4⋅311=225−4811.
Calculate roots: Calculate the roots using the quadratic formula. x=8−15±225−4811.
Simplify roots: Simplify the roots.The roots cannot be simplified further without a calculator, but they represent the two linear factors of the quadratic term.
Write final expression: Write the final expression as a product of linear factors.The final expression is the product of the binomial squared and its linear factors: (x−root1)(x−root2)(4x2+15x+311).
Realize factorization mistake: Realize a mistake has been made in the factorization process. The original approach to factor the quadratic term within the binomial was incorrect because we cannot factor 4x2+15x+311 into linear factors with real coefficients. We need to go back and find the correct linear factors.
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