Math Problem Statement

Solve the following simultaneous equations algebraically: 7x + 5y = 8 3x - 2y = -9

Solution

The system of simultaneous equations provided in the image is:

7x+5y=87x + 5y = 8 3x2y=93x - 2y = -9

We can solve this system algebraically using either substitution or elimination. I'll use the elimination method here. The goal is to eliminate one variable and solve for the other.

Step 1: Multiply both equations to make the coefficients of one variable (e.g., yy) the same

To eliminate yy, we need the coefficients of yy in both equations to be equal (in absolute value). We can do this by multiplying the first equation by 2 and the second equation by 5.

2(7x+5y)=2(8)(Multiply the first equation by 2)2(7x + 5y) = 2(8) \quad \text{(Multiply the first equation by 2)} 14x+10y=1614x + 10y = 16 5(3x2y)=5(9)(Multiply the second equation by 5)5(3x - 2y) = 5(-9) \quad \text{(Multiply the second equation by 5)} 15x10y=4515x - 10y = -45

Step 2: Add the two equations to eliminate yy

Now, we add the two equations:

(14x+10y)+(15x10y)=16+(45)(14x + 10y) + (15x - 10y) = 16 + (-45) 14x+15x=2914x + 15x = -29 29x=2929x = -29

Step 3: Solve for xx

x=2929=1x = \frac{-29}{29} = -1

Step 4: Substitute x=1x = -1 into one of the original equations to find yy

Substitute x=1x = -1 into the first equation:

7(1)+5y=87(-1) + 5y = 8 7+5y=8-7 + 5y = 8 5y=8+75y = 8 + 7 5y=155y = 15 y=155=3y = \frac{15}{5} = 3

Solution:

The solution to the system of equations is: x=1,y=3x = -1, \quad y = 3

Would you like more details or have any further questions?

Here are 5 related questions you might explore:

  1. How would the substitution method work for this system of equations?
  2. Can this system of equations be solved graphically? How?
  3. What happens if the system has no solution or infinitely many solutions?
  4. How can we verify the solution by plugging the values of xx and yy back into the equations?
  5. What are some real-world applications of solving simultaneous equations?

Tip: When using elimination, make sure the variables you're eliminating have coefficients that are opposites to avoid mistakes when adding or subtracting equations!

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Algebra
Simultaneous Equations
Linear Equations

Formulas

Elimination method
Substitution method

Theorems

System of Linear Equations
Consistency of Solutions

Suitable Grade Level

Grades 9-11