Questions: 7. 2x^2+4x-30 8. 8x^2+47x-6 9. Multiply each of the binomials. Give your answers in standard form. a) (x+3)(x+4) b) (x+6)(x-6) c) 2x(x+5) d) (3x+2)(2x-3)

7. 2x^2+4x-30
8. 8x^2+47x-6
9. Multiply each of the binomials. Give your answers in standard form.
a) (x+3)(x+4) b) (x+6)(x-6)
c) 2x(x+5) d) (3x+2)(2x-3)
Transcript text: 7. $2 x^{2}+4 x-30$ 8. $8 x^{2}+47 x-6$ 9. Multiply each of the binomials. Give your answers in standard form. \begin{tabular}{|ll|ll|} \hline a) & $(x+3)(x+4)$ & b) & $(x+6)(x-6)$ \\ & & \\ \hline c) & $2 x(x+5)$ & d) & $(3 x+2)(2 x-3)$ \\ \hline \end{tabular}
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Solution

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Solution Steps

Step 1: Solve \(2x^{2} + 4x - 30\)
  1. Factor out the greatest common factor (GCF):
    \(2x^{2} + 4x - 30 = 2(x^{2} + 2x - 15)\).
  2. Factor the quadratic expression inside the parentheses:
    \(x^{2} + 2x - 15 = (x + 5)(x - 3)\).
  3. Combine the results:
    \(2(x + 5)(x - 3)\).

Step 2: Solve \(8x^{2} + 47x - 6\)
  1. Use the quadratic formula:
    \(x = \frac{-b \pm \sqrt{b^{2} - 4ac}}{2a}\), where \(a = 8\), \(b = 47\), and \(c = -6\).
  2. Calculate the discriminant:
    \(\Delta = b^{2} - 4ac = 47^{2} - 4(8)(-6) = 2209 + 192 = 2401\).
  3. Compute the square root of the discriminant:
    \(\sqrt{2401} = 49\).
  4. Substitute into the quadratic formula:
    \(x = \frac{-47 \pm 49}{16}\).
  5. Solve for the two roots:
    \(x = \frac{2}{16} = \frac{1}{8}\) and \(x = \frac{-96}{16} = -6\).
  6. Write the factored form:
    \(8(x - \frac{1}{8})(x + 6)\).

Step 3: Multiply the binomials in part (a) \((x+3)(x+4)\)
  1. Use the distributive property (FOIL method):
    \((x + 3)(x + 4) = x \cdot x + x \cdot 4 + 3 \cdot x + 3 \cdot 4\).
  2. Simplify each term:
    \(x^{2} + 4x + 3x + 12\).
  3. Combine like terms:
    \(x^{2} + 7x + 12\).

The remaining questions are left unanswered as per the guidelines.

Final Answer

  1. \(2(x + 5)(x - 3)\)
  2. \(8(x - \frac{1}{8})(x + 6)\)
  3. a) \(x^{2} + 7x + 12\)
  4. b) \(x^{2} - 36\)
  5. c) \(2x^{2} + 10x\)
  6. d) \(6x^{2} - 5x - 6\)
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