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Solve for x: $$\frac{3x + 1}{5} + \frac{x - 2}{2} = \frac{47}{10}$$ Solve the simultaneous equations: $$x - 5y = -13$$ $$x^2 + y^2 = 13$$ - Leaving Cert Mathematics - Question 4 - 2019

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Question 4

Solve-for-x:--$$\frac{3x-+-1}{5}-+-\frac{x---2}{2}-=-\frac{47}{10}$$--Solve-the-simultaneous-equations:--$$x---5y-=--13$$--$$x^2-+-y^2-=-13$$-Leaving Cert Mathematics-Question 4-2019.png

Solve for x: $$\frac{3x + 1}{5} + \frac{x - 2}{2} = \frac{47}{10}$$ Solve the simultaneous equations: $$x - 5y = -13$$ $$x^2 + y^2 = 13$$

Worked Solution & Example Answer:Solve for x: $$\frac{3x + 1}{5} + \frac{x - 2}{2} = \frac{47}{10}$$ Solve the simultaneous equations: $$x - 5y = -13$$ $$x^2 + y^2 = 13$$ - Leaving Cert Mathematics - Question 4 - 2019

Step 1

Solve for x:

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Answer

To solve for x, we start with the equation:

3x+15+x22=4710\frac{3x + 1}{5} + \frac{x - 2}{2} = \frac{47}{10}

Step 1: Find a common denominator.

  • The common denominator for 5, 2, and 10 is 10. Therefore, we can multiply the entire equation by 10:

10(3x+15)+10(x22)=10(4710)10 \left(\frac{3x + 1}{5}\right) + 10 \left(\frac{x - 2}{2}\right) = 10 \left(\frac{47}{10}\right)

Step 2: Simplify the equation.

  • This results in:

2(3x+1)+5(x2)=472(3x + 1) + 5(x - 2) = 47

Step 3: Expand the equation.

  • Distributing the constants gives us:

6x+2+5x10=476x + 2 + 5x - 10 = 47

Step 4: Combine like terms.

  • To combine the x terms:

11x8=4711x - 8 = 47

Step 5: Isolate x.

  • Adding 8 to both sides:

11x=5511x = 55

  • Divide by 11:

x=5x = 5

Step 2

Solve the simultaneous equations:

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Answer

To solve the simultaneous equations:

  1. Identify the equations:

    • x5y=13x - 5y = -13 (Equation 1)
    • x2+y2=13x^2 + y^2 = 13 (Equation 2)
  2. Rearrange Equation 1 to express x in terms of y: x=5y13x = 5y - 13

  3. Substitute x in Equation 2:

    • Substitute into Equation 2:

    (5y13)2+y2=13(5y - 13)^2 + y^2 = 13

  4. Expand and simplify:

    • Expanding gives:

    25y2130y+169+y2=1325y^2 - 130y + 169 + y^2 = 13

    • Combine like terms:

    26y2130y+156=026y^2 - 130y + 156 = 0

  5. Factoring the quadratic equation:

    • We can factor the quadratic as:

    (y6)(y2)=0(y - 6)(y - 2) = 0

    This yields:

    y=6 or y=2y = 6 \text{ or } y = 2

  6. Substituting back for x:

    • For y=2y = 2:

    x=5(2)13=3x = 5(2) - 13 = -3

    • For y=6y = 6:

    x=5(6)13=17x = 5(6) - 13 = 17

  7. Final Solutions:

    • Thus, the solutions are:

    (3,2) and (17,6)(-3, 2) \text{ and } (17, 6)

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