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a) Simplify $3(4 - 5x) - 2(5 - 6x)$ - Leaving Cert Mathematics - Question 3 - 2015

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a)-Simplify-$3(4---5x)---2(5---6x)$-Leaving Cert Mathematics-Question 3-2015.png

a) Simplify $3(4 - 5x) - 2(5 - 6x)$. b) List all the values of $x$ that satisfy the inequality $2 - 3x \geq -6$, \( x \in \mathbb{N}$. c) $g(x)$ is a function ... show full transcript

Worked Solution & Example Answer:a) Simplify $3(4 - 5x) - 2(5 - 6x)$ - Leaving Cert Mathematics - Question 3 - 2015

Step 1

a) Simplify $3(4 - 5x) - 2(5 - 6x)$

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Answer

To simplify the expression, distribute the constants:

  1. 3(45x)=1215x3(4 - 5x) = 12 - 15x

  2. 2(56x)=10+12x-2(5 - 6x) = -10 + 12x

  3. Combine these results:

    1215x10+12x=23x12 - 15x - 10 + 12x = 2 - 3x

Thus, the simplified expression is 23x2 - 3x.

Step 2

b) List all the values of $x$ that satisfy the inequality $2 - 3x \geq -6$, \( x \in \mathbb{N}$

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Answer

  1. Start with the inequality:
    [ 2 - 3x \geq -6 ]
  2. Subtract 2 from both sides:
    [ -3x \geq -8 ]
  3. Divide by -3 (remember to flip the inequality):
    [ x \leq \frac{8}{3} ]
  4. Since ( x \in \mathbb{N} ), valid values are 11 and 22. Therefore, ( x \in {1, 2}$.

Step 3

c) $g(x)$ is a function and $(2 - 3x) \times g(x) = 15x^2 - 22x + 8$, for all $x \in \mathbb{R}$. Find $g(x)$.

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Answer

To find g(x)g(x), we start with the equation:

  1. Rearranging gives:
    [ g(x) = \frac{15x^2 - 22x + 8}{2 - 3x} ]
  2. To solve, we can factor or simplify:
    • Setting up:
      [ g(x) = \frac{15x^2 - 10x - 12x + 8}{2 - 3x} ]
    • Observe: this cancellation might give us insights into g(x)g(x).
  3. After performing polynomial long division or identifying patterns, we find that:
    [ g(x) = -5x + 4 ]
    This is our final function value.

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