Math Problem Statement

Solve the system of equations: 5x + 6y = -6 and 7x - 3y = -12.

Solution

To solve this system of equations:

  1. 5x+6y=65x + 6y = -6
  2. 7x3y=127x - 3y = -12

Let's use the elimination method to find the values of xx and yy.

Step 1: Make the Coefficients of yy Equal

To eliminate yy, we can multiply the first equation by 3 and the second equation by 6:

3(5x+6y)=3(6)15x+18y=183(5x + 6y) = 3(-6) \Rightarrow 15x + 18y = -18 6(7x3y)=6(12)42x18y=726(7x - 3y) = 6(-12) \Rightarrow 42x - 18y = -72

Now we have:

  1. 15x+18y=1815x + 18y = -18
  2. 42x18y=7242x - 18y = -72

Step 2: Add the Equations

Add the two equations to eliminate yy:

(15x+18y)+(42x18y)=1872(15x + 18y) + (42x - 18y) = -18 - 72 57x=9057x = -90

Step 3: Solve for xx

Divide both sides by 57:

x=9057=3019x = \frac{-90}{57} = -\frac{30}{19}

Step 4: Substitute xx Back into One of the Original Equations

Now, substitute x=3019x = -\frac{30}{19} into the first equation to solve for yy:

5(3019)+6y=65\left(-\frac{30}{19}\right) + 6y = -6 15019+6y=6-\frac{150}{19} + 6y = -6

Convert -6 to a fraction with a denominator of 19:

15019+6y=11419-\frac{150}{19} + 6y = -\frac{114}{19}

Add 15019\frac{150}{19} to both sides:

6y=36196y = \frac{36}{19}

Now, divide by 6:

y=3619×16=619y = \frac{36}{19} \times \frac{1}{6} = \frac{6}{19}

Solution

The solution to the system is: x=3019,y=619x = -\frac{30}{19}, \quad y = \frac{6}{19}

Would you like further details on each step or have any questions?


Here are some related questions to explore further:

  1. How can we solve this system of equations using substitution?
  2. What is the significance of using fractions instead of decimal approximations in exact solutions?
  3. Can we solve this system by graphing, and what does the solution represent graphically?
  4. How does the elimination method compare to substitution in terms of efficiency?
  5. What strategies can we use if both elimination and substitution methods seem challenging?

Tip: Always check your solution by plugging the values back into the original equations to ensure accuracy.

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Math Problem Analysis

Mathematical Concepts

Algebra
Systems of Equations
Elimination Method

Formulas

Linear equation in two variables
Elimination method for solving systems

Theorems

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Suitable Grade Level

Grades 8-10