Math Problem Statement

Solve the following system of equations: 9x + 2y = 19 and 6x + 7y = -10.

Solution

The given system of equations is:

9x+2y=199x + 2y = 19 6x+7y=106x + 7y = -10

We will solve this system using substitution or elimination. Let's proceed by using the elimination method.

Step 1: Eliminate one variable

To eliminate one of the variables, we'll make the coefficients of either xx or yy the same in both equations. Let's focus on eliminating xx.

Multiply the first equation by 6 and the second equation by 9 to align the coefficients of xx:

6(9x+2y)=6(19)54x+12y=1146(9x + 2y) = 6(19) \quad \Rightarrow \quad 54x + 12y = 114 9(6x+7y)=9(10)54x+63y=909(6x + 7y) = 9(-10) \quad \Rightarrow \quad 54x + 63y = -90

Step 2: Subtract the equations

Now subtract the second equation from the first:

(54x+12y)(54x+63y)=114(90)(54x + 12y) - (54x + 63y) = 114 - (-90) 54x+12y54x63y=114+9054x + 12y - 54x - 63y = 114 + 90 51y=204-51y = 204

Step 3: Solve for yy

y=20451=4y = \frac{204}{-51} = -4

Step 4: Substitute y=4y = -4 into one of the original equations

We substitute y=4y = -4 into the first equation:

9x+2(4)=199x + 2(-4) = 19 9x8=199x - 8 = 19 9x=19+8=279x = 19 + 8 = 27 x=279=3x = \frac{27}{9} = 3

Final Answer:

x=3,y=4x = 3, \quad y = -4

Would you like further details or explanations on any step?

Here are some additional questions that may help expand your understanding:

  1. How would you solve this system using the substitution method?
  2. How can the determinant method (Cramer's Rule) be used to solve this system of equations?
  3. What happens if both equations are multiplied to eliminate yy instead of xx?
  4. Can graphing both equations provide a visual confirmation of the solution?
  5. How would solving the system change if one of the constants was different?

Tip: When using the elimination method, try to choose the variable that simplifies the arithmetic the most.

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Math Problem Analysis

Mathematical Concepts

Algebra
Linear Systems of Equations
Elimination Method

Formulas

Linear equation in two variables: ax + by = c
Elimination method for solving systems of equations

Theorems

Elimination Method: Align coefficients to eliminate one variable

Suitable Grade Level

Grades 9-10