Math Problem Statement

-3x + 7y = -16, -9x + 5y = 16. Solve for x and y.

Solution

The image you uploaded contains a system of linear equations. Here are the equations from the image:

  1. 3x+7y=16-3x + 7y = -16
  2. 9x+5y=16-9x + 5y = 16

Let's solve this system of equations.

Step 1: Use the method of elimination or substitution to solve the system.

Let's solve this by elimination. To eliminate one of the variables, we need to make the coefficients of xx or yy the same in both equations. We can multiply the first equation by 3 and the second equation by 1 to make the coefficients of xx the same.

  • Equation 1: 3x+7y=16-3x + 7y = -16 becomes: (3x+7y)×3=16×3    9x+21y=48(-3x + 7y) \times 3 = -16 \times 3 \implies -9x + 21y = -48
  • Equation 2: 9x+5y=16-9x + 5y = 16 remains the same.

Now we have the system:

  1. 9x+21y=48-9x + 21y = -48
  2. 9x+5y=16-9x + 5y = 16

Step 2: Subtract the second equation from the first to eliminate xx:

(9x+21y)(9x+5y)=4816(-9x + 21y) - (-9x + 5y) = -48 - 16 Simplifying:

9x+21y+9x5y=64    16y=64-9x + 21y + 9x - 5y = -64 \implies 16y = -64

Step 3: Solve for yy:

y=6416=4y = \frac{-64}{16} = -4

Step 4: Substitute y=4y = -4 into one of the original equations to solve for xx. Using the first equation:

3x+7(4)=16-3x + 7(-4) = -16 3x28=16-3x - 28 = -16 3x=16+28    3x=12-3x = -16 + 28 \implies -3x = 12 x=123=4x = \frac{12}{-3} = -4

Final Answer:

The solution to the system of equations is: x=4,y=4x = -4, \quad y = -4

Let me know if you would like a more detailed explanation or if you have any further questions!

Here are some follow-up questions:

  1. What other methods can be used to solve systems of linear equations?
  2. How do you check the solution of a system of equations?
  3. What happens if a system of equations has no solution?
  4. Can you solve systems of equations involving more than two variables?
  5. What is the graphical representation of the solution to a system of linear equations?

Tip: When solving a system of linear equations, always try to choose the method (substitution or elimination) that makes the math simpler.

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Math Problem Analysis

Mathematical Concepts

Algebra
Systems of Linear Equations
Elimination Method

Formulas

Elimination method: Multiply equations to align coefficients and subtract/add to eliminate a variable.
Substitution method: Express one variable in terms of another and substitute into an equation.

Theorems

Linear System Theorem

Suitable Grade Level

Grades 8-10