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Rewrite the expression as a product of four linear factors:

(4x^(2)+15 x)^(2)+20(4x^(2)+15 x)+99
Answer:

Rewrite the expression as a product of four linear factors:\newline(4x2+15x)2+20(4x2+15x)+99 \left(4 x^{2}+15 x\right)^{2}+20\left(4 x^{2}+15 x\right)+99 \newlineAnswer:

Full solution

Q. Rewrite the expression as a product of four linear factors:\newline(4x2+15x)2+20(4x2+15x)+99 \left(4 x^{2}+15 x\right)^{2}+20\left(4 x^{2}+15 x\right)+99 \newlineAnswer:
  1. Recognize perfect square trinomial: Recognize the given expression as a perfect square trinomial. The expression is in the form of (A2+2AB+B2)(A^2 + 2AB + B^2), where A=(4x2+15x)A = (4x^2 + 15x) and BB is a number we need to find such that B2=99B^2 = 99 and 2AB=20(4x2+15x)2AB = 20(4x^2 + 15x).
  2. Find value of B: Find the value of BB. We know that B2=99B^2 = 99, so BB is the square root of 9999. Since 9999 is not a perfect square, we can simplify it to B=9×11=311B = \sqrt{9\times11} = 3\sqrt{11}.
  3. Verify 2AB2AB matches: Verify that 2AB2AB matches the middle term of the original expression.\newline2AB=2×(4x2+15x)×311=20(4x2+15x)2AB = 2 \times (4x^2 + 15x) \times 3\sqrt{11} = 20(4x^2 + 15x) after simplifying.\newlineThis matches the middle term of the original expression, confirming that B=311B = 3\sqrt{11} is correct.
  4. Write as perfect square: Write the expression as a perfect square.\newlineThe original expression can now be written as a perfect square: [(4x2+15x)+311]2[(4x^2 + 15x) + 3\sqrt{11}]^2.
  5. Factor binomial squared: Factor the perfect square as a binomial squared.\newlineThe expression [(4x2+15x)+311]2[(4x^2 + 15x) + 3\sqrt{11}]^2 is the square of the binomial (4x2+15x+311)(4x^2 + 15x + 3\sqrt{11}).
  6. Factor quadratic term: Factor the quadratic term within the binomial.\newlineTo factor 4x2+15x+3114x^2 + 15x + 3\sqrt{11}, we look for two numbers that multiply to 43114\cdot3\sqrt{11} and add to 1515. However, this is not possible with integers, so we need to use the quadratic formula to find the roots of 4x2+15x+311=04x^2 + 15x + 3\sqrt{11} = 0.
  7. Apply quadratic formula: Apply the quadratic formula to find the roots.\newlineThe quadratic formula is x=b±b24ac2ax = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}, where a=4a = 4, b=15b = 15, and c=311c = 3\sqrt{11}.
  8. Calculate discriminant: Calculate the discriminant b24acb^2 - 4ac. The discriminant is 15244311=225481115^2 - 4\cdot4\cdot3\sqrt{11} = 225 - 48\sqrt{11}.
  9. Calculate roots: Calculate the roots using the quadratic formula. x=15±22548118x = \frac{{-15 \pm \sqrt{{225 - 48\sqrt{11}}}}}{8}.
  10. Simplify roots: Simplify the roots.\newlineThe roots cannot be simplified further without a calculator, but they represent the two linear factors of the quadratic term.
  11. Write final expression: Write the final expression as a product of linear factors.\newlineThe final expression is the product of the binomial squared and its linear factors: (xroot1)(xroot2)(4x2+15x+311)(x - \text{root1})(x - \text{root2})(4x^2 + 15x + 3\sqrt{11}).
  12. 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+3114x^2 + 15x + 3\sqrt{11} into linear factors with real coefficients. We need to go back and find the correct linear factors.

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