Math Problem Statement

solve by the substitution method. 4x+8y=12 and 3x-8y=9

what is the solution of the system?

Solution

To solve the system of equations using the substitution method, we first isolate one variable in one equation and substitute it into the other equation.

Step 1: Write down the equations

  1. 4x+8y=124x + 8y = 12
  2. 3x8y=93x - 8y = 9

Step 2: Solve one equation for one variable

From the first equation: 4x+8y=12    4x=128y    x=128y4    x=32y4x + 8y = 12 \implies 4x = 12 - 8y \implies x = \frac{12 - 8y}{4} \implies x = 3 - 2y

Step 3: Substitute x=32yx = 3 - 2y into the second equation

Substitute x=32yx = 3 - 2y into 3x8y=93x - 8y = 9: 3(32y)8y=93(3 - 2y) - 8y = 9 Simplify: 96y8y=9    914y=99 - 6y - 8y = 9 \implies 9 - 14y = 9 14y=0    y=0-14y = 0 \implies y = 0

Step 4: Substitute y=0y = 0 back into x=32yx = 3 - 2y

x=32(0)    x=3x = 3 - 2(0) \implies x = 3

Solution:

The solution to the system is: x=3,y=0x = 3, \, y = 0

Final Answer:

(x,y)=(3,0)(x, y) = (3, 0)

Would you like to see a graphical verification or additional details?


Five related questions:

  1. How is the substitution method different from the elimination method?
  2. Can this system be solved graphically to verify the solution?
  3. How do we interpret the solution of a linear system in terms of lines?
  4. What are the steps to isolate a variable in more complex systems?
  5. What if the equations represent parallel lines? What happens then?

Tip: Always simplify equations as much as possible before substituting to avoid unnecessary complexity.

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Math Problem Analysis

Mathematical Concepts

Algebra
System of Equations
Substitution Method

Formulas

Substitution method for solving linear systems

Theorems

Substitution theorem for solving linear equations

Suitable Grade Level

Grades 7-9